Call processing method and communication device

Abstract

The present application provides a call processing method and communication device, the method comprising: a first terminal device receives first information, wherein the first terminal device resides in a 5G network, the LTE capability of the first terminal device is in a closed state, the first information is used by the first terminal device to determine to enter the circuit switched CS domain to wait for a call, or the first information is used by the first terminal device to turn on the LTE capability; the first terminal device enters the CS domain to wait for a call or the first terminal device turns on the LTE capability. Based on the method described in the present application, since the LTE capability of the first terminal device is turned off, when the network device determines that it cannot establish a voice data channel for the first terminal device, the first terminal device can be made to enter the CS domain to wait for a call so as to call the first terminal device through the CS domain, or the first terminal device can be made to turn on the LTE capability so as to call through the IMS domain, which is conducive to avoiding call failures.

Description

Technical Field

[0001] The present application relates to the field of communication technology, and in particular to a call processing method and a communication device. Background Art

[0002] The fifth generation of mobile communication technology (5 th In the early stage of 5G network deployment, some operators' networks do not support the establishment of voice and data channels in 5G networks, that is, they do not support voice over new radio (VoNR); or the NR network is not well deployed, and the probability of failure to establish voice and data channels in 5G networks is high. In order to solve this problem, the industry has proposed an evolved packet system fallback (EPS fallback) solution. That is, during the process of establishing a voice and data channel, if the 5G base station determines that the voice and data channel cannot be established in the 5G network, the 5G base station initiates a handover or redirection of the UE to the fourth generation mobile communication technology (4G). th generation, 4G) process, and establish a voice data channel for the UE in the 4G network, thereby completing the establishment of the voice call.

[0003] When a UE is on a 4G network, it must perform a registration (attach) or TAU procedure. If the UE is in an area with weak 4G signal, such as a basement, it may experience five consecutive attach or TAU failures within the 4G network. The standard stipulates that if the TAU or Attach procedure fails five times, the UE will disable LTE and initiate T3402 (default 12 minutes). This means that the UE will remain LTE-disabled until T3402 expires.

[0004] If a UE disables LTE, it will not carry 4G capability information when registering within 5G. The 5G core network's access and mobility management function (AMF) will deem the UE to be 4G-incapable. The AMF will then notify the 5G base station (gNB or NG RAN) that the UE cannot fall back to 4G for voice services. This can cause calls to fail when the 5G network is unable to establish a voice and data channel. This can cause users to miss calls because the network cannot fall back to 4G to establish a voice and data channel. Summary of the Invention

[0005] The embodiments of the present application provide a call processing method and a communication device, which are helpful in avoiding call failure after the LTE capability of the UE is disabled.

[0006] In a first aspect, the present application provides a call processing method, which includes: a first terminal device receives first information, wherein the first terminal device resides in a fifth-generation mobile communication technology 5G network, and the long-term evolution LTE capability of the first terminal device is in a closed state, and the first information is used by the first terminal device to determine to enter a circuit-switched CS domain to wait for a call, or the first information is used for the first terminal device to turn on the LTE capability; the first terminal device enters the CS domain to wait for a call or the first terminal device turns on the LTE capability.

[0007] Based on the method described in the first aspect, since the LTE capability of the first terminal device is turned off, when the network device determines that it cannot establish a voice data channel for the first terminal device, the first terminal device can be enabled to enter the CS domain to wait for a call so that a call can be made to the first terminal device through the CS domain, or the first terminal device can be enabled to enable the LTE capability so that a call can be made through the IMS domain, which is conducive to avoiding call failure.

[0008] In a first possible implementation, the first terminal device may also receive a first call request in the IMS domain before receiving the first information. Based on the first possible implementation, the first terminal device receives the first information after receiving the first call request. This can avoid call failures in scenarios where the 5G network does not support VoNR, or where the 5G network supports VoNR but the 5G network signal is poor, and has a wide range of application scenarios.

[0009] In a second possible implementation, the first terminal device receives the first information by: the first terminal device receives the first information sent by an access and mobility management function (AMF). Based on the second possible implementation, the first terminal device can be triggered to reselect to a CS network or enable LTE capabilities during the called party's access domain selection phase. This method is executed early, shortening call establishment time and reducing waiting time for the calling UE.

[0010] In combination with any one of the first aspect, the first possible implementation manner, and the second possible implementation manner, in a third possible implementation manner, a specific implementation of the first terminal device entering the CS domain to wait for a call is as follows: the first terminal device reselects to a second-generation mobile communication technology (2G) network or a third-generation mobile communication technology (3G) network; the first terminal device sends an attach request or a location update request to a fifth network device; and the first terminal device waits for a call in the CS domain. Based on the third possible implementation manner, the CS domain can be successfully entered.

[0011] In combination with any one of the first aspect, the first possible implementation manner, the second possible implementation manner, and the third possible implementation manner, in a fourth possible implementation manner, after the first terminal device enters the CS domain to wait for a call, the first terminal device may further receive a call request in the CS domain. Based on the fourth possible implementation manner, the first terminal device can successfully receive the call request, avoiding call failure.

[0012] In combination with any one of the first aspect, the first possible implementation, and the second possible implementation, in a fifth possible implementation, after the first terminal device enables LTE capabilities, it may further send a registration request to the fourth network device, where the registration request carries Long Term Evolution (LTE) capability information of the first terminal device; and the first terminal device may further receive a second call request in the IP Multimedia System (IMS) domain. Based on the fifth possible implementation, the latest capability information of the first terminal device can be reported to the network in a timely manner.

[0013] In a second aspect, the present application provides a call processing method, which includes: a first network device receives second information, and the second information is used by the first network device to determine that a voice data channel cannot be established for a first terminal device; the first network device sends third information to the second network device; the first network device sends first information to the first terminal device; wherein, the third information is used by the second network device to determine to call the first terminal device through the circuit switching CS domain, and the first information is used by the first terminal device to determine to enter the CS domain to wait for the call; or, the third information is used by the second network device to determine to call the first terminal device through the IP multimedia system IMS domain, and the first information is used by the first terminal device to determine to enable the long-term evolution LTE capability.

[0014] Based on the method described in the second aspect, when the LTE capability of the first terminal device is turned off, if the network side determines that it cannot establish a voice data channel for the first terminal device, the first terminal device can be enabled to enter the CS domain to wait for a call, and the network side can call the first terminal device through the CS domain; or the first terminal device can be enabled to have the LTE capability, and the network side can call through the IMS domain, which is conducive to avoiding call failure.

[0015] In a first possible implementation, the second information is further used by the first network device to determine whether the Long Term Evolution (LTE) capability of the first terminal device has been disabled. By notifying the second network device of the disabled LTE capability of the first terminal device, the second network device can accurately determine whether it is necessary to place a call to the first terminal device again in the CS domain, thereby avoiding terminating the call upon receiving information confirming that a voice and data channel cannot be established for the first terminal device.

[0016] In conjunction with the first aspect or the first possible implementation, in a second possible implementation, the third information is further used by the second network device to determine whether the LTE capability of the first terminal device is disabled. By notifying AS-1 that the LTE capability of UE-1 is disabled, AS-1 can be informed of the reason for re-calling UE-1 in the CS domain.

[0017] In combination with the first aspect, the first possible implementation method, and any one of the second possible implementation methods, in a third possible implementation method, the second network device sends a first call request to the first terminal device through the IP Multimedia System IMS domain; the second network device receives the third information sent by the first network device; and the second network device sends a second call request to the first terminal device through the CS domain or the IMS domain. Based on the third possible implementation method, when the LTE capability of the first terminal device is turned off, if the network side determines that it cannot establish a voice data channel for the first terminal device, the first terminal device can be made to enter the CS domain to wait for the call, and the network side can call the first terminal device through the CS domain; or the first terminal device can be made to turn on the LTE capability, and the network side can call through the IMS domain, which is conducive to avoiding call failure.

[0018] In conjunction with the third possible implementation, in a fourth possible implementation, the second network device sending the second call request to the first terminal device via the CS domain is specifically implemented as follows: the second network device sends a first request to the third network device, the first request being used to request fourth information for routing the call to the first terminal device via the CS domain; the second network device receives the fourth information sent by the third network device; and the second network device sends the second call request to the first terminal device via the CS domain based on the fourth information. Based on the fourth possible implementation, the second network device can obtain the fourth information for routing the call to the first terminal device via the CS domain, and send the second call request to the first terminal device based on the fourth information, thereby accurately routing the call to the first terminal device.

[0019] In conjunction with the fourth possible implementation, in a fifth possible implementation, the first request carries fifth information; based on the fifth information, the third network device may send fourth information to the second network device after determining that the first terminal device has completed CS domain registration or location update. By sending the fourth information to the second network device only after determining that the first terminal device has completed CS domain registration or location update, it is possible to prevent the second network device from placing a CS call to the first terminal device before the first terminal device completes CS registration, thereby preventing the call from failing again.

[0020] In combination with the third possible implementation, in a sixth possible implementation, the specific implementation method of the second network device sending the second call request to the first terminal device through the IMS domain is as follows: the second network device sends a first request to the third network device, the first request is used to request sixth information, and the sixth information is used to determine whether a call can be made to the first terminal device through the IMS domain; the second network device receives the sixth information sent by the third network device; if the second network device determines that a call can be made to the first terminal device through the IMS domain based on the sixth information, the second network device sends a second call request to the first terminal device through the IMS domain. Based on the sixth possible implementation, the second network device can query other network devices whether the IMS domain can currently be used to call the first terminal device, thereby avoiding further call failure through the IMS domain.

[0021] In combination with the sixth possible implementation, in a seventh possible implementation, the first request carries the seventh information. The third network device may, based on the seventh information, send a second request carrying the eighth information to the fourth network device, where the second request is used to request the sixth information. The fourth network device may, based on the eighth information, send the sixth information to the third network device after determining that the first terminal device has activated Long Term Evolution (LTE) capabilities. The third network device may also send the sixth information to the second network device. Based on the seventh possible implementation, sending the sixth information to the third network device after determining that the first terminal device has activated LTE capabilities helps prevent the second network device from placing an IMS call to the first terminal device before the first terminal device activates LTE capabilities, thereby preventing the call from failing again.

[0022] In combination with the fourth or sixth possible implementation manner, in an eighth possible implementation manner, the third information includes a timer; and a specific implementation manner of the second network device sending the first request to the third network device is: the second network device sends the first request to the third network device when the timer expires. Based on the eighth possible implementation manner, the second network device sends the first request to the third network device when the timer expires, which helps to prevent the second network device from making an IMS call to the first terminal device before the first terminal device activates LTE capabilities, thereby avoiding further call failure.

[0023] In a third aspect, the present application provides a call processing method, which includes: a fourth network device determines that a call cannot be made to a first terminal device through an IP multimedia system IMS domain; the fourth network device sends a first information to the first terminal device, and the first information is used by the first terminal device to determine to enter a CS domain to wait for a call; the fourth network device sends a second information to a third network device, and the second information is used to determine that a call cannot be made to the first terminal device through the IMS domain.

[0024] Based on the method described in the third aspect, when a call to the first terminal device cannot be made through the IMS domain, the first terminal device can enter the CS domain to wait for the call, and the network side can initiate a call to the first terminal device through the CS domain, which helps to avoid call failure. In addition, the first terminal device can be triggered to reselect to the CS network or enable LTE capabilities during the called access domain selection phase. The method is executed at an early timing, which can shorten the call establishment time and reduce the waiting time of the calling UE.

[0025] In a first possible implementation, the specific implementation method for the fourth network device to determine that a call cannot be made to the first terminal device through the IP Multimedia System (IMS) domain is as follows: the fourth network device determines that a call cannot be made to the first terminal device through the IMS domain based on the capability information and / or network capability information of the first terminal device; the capability information of the first terminal device includes that the first terminal device does not support Long Term Evolution (LTE); the network capability information includes one or more combinations of the following: the network does not support Voice over New Radio (VoNR); the network supports Evolved Packet System (EPS) fallback; the network does not support the fifth generation mobile communication technology (5G) and falls back to 2G / 3G for call reception. Based on the first possible implementation, it is possible to accurately determine whether a call can be made to the first terminal device through the IMS domain, which helps to avoid call failures.

[0026] In conjunction with the third aspect or the first possible implementation, in a second possible implementation, the fourth network device sends third information to the third network device; based on the third information, the third network device sends second information to the second network device after determining that the first terminal device has completed CS domain registration or location update. Based on the second possible implementation, by sending the second information to the second network device after determining that the first terminal device has completed CS domain registration or location update, this helps prevent the second network device from placing a CS call to the first terminal device before the first terminal device's CS registration is completed, thereby avoiding further call failure.

[0027] In conjunction with the third aspect or the first possible implementation, in the third possible implementation, the fourth network device sends a timer to the third network device; and when the timer expires, the third network device sends second information to the second network device. Based on the third possible implementation, by sending the second information to the second network device when the timer expires, it is helpful to prevent the second network device from placing a CS call to the first terminal device before the CS registration of the first terminal device is completed, thereby avoiding further call failure.

[0028] In combination with the second or third possible implementations, in a fourth possible implementation, the third network device sends fourth information to the second network device, where the fourth information is used to route the call to the first terminal device via the circuit-switched (CS) domain. Based on the fourth possible implementation, the call is successfully routed to the first terminal device. Furthermore, the third network device can proactively send the fourth information to the second network device, which helps reduce signaling interactions.

[0029] In combination with any one of the third aspect, the first possible implementation, the second possible implementation, the third possible implementation, and the fourth possible implementation, in a fifth possible implementation, the fourth network device is an access and mobility management function (AMF). The fourth network device performs this method, which can make minor changes to existing standards.

[0030] In a fourth aspect, the present application provides a call processing method, which includes: the fourth network device determines that a call cannot be made to the first terminal device through the IP Multimedia System IMS domain; the fourth network device sends first information to the first terminal device, and the first information is used by the first terminal device to determine whether to enable the Long Term Evolution LTE capability; after the fourth network device determines that the first terminal device has enabled the LTE capability, the fourth network device sends second information to the third network device, and the second information is used to determine that a call can be made through the IMS domain.

[0031] Based on the method described in the fourth aspect, when a call to the first terminal device cannot be made through the IMS domain, the first terminal device can be enabled to enable LTE capabilities, and the network side can initiate a call to the first terminal device through the IMS domain, which helps to avoid call failure. In addition, the first terminal device can be triggered to reselect to the CS network or enable LTE capabilities during the called access domain selection phase. The method is executed at an early timing, which can shorten the call establishment time and reduce the waiting time of the calling UE.

[0032] In a first possible implementation, the specific implementation method for the fourth network device to determine that a call cannot be made to the first terminal device through the IP Multimedia System (IMS) domain is as follows: the fourth network device determines that a call cannot be made to the first terminal device through the IP Multimedia System (IMS) domain based on the capability information and / or network capability information of the first terminal device; the capability information of the first terminal device includes that the first terminal device does not support Long Term Evolution (LTE); and the network capability information includes one or more combinations of the following: the network does not support Voice over New Radio (VoNR), supports Evolved Packet System (EPS) fallback, and the network does not support the fifth generation mobile communication technology (5G) and falls back to the second generation mobile communication technology (2G) / third generation mobile communication technology (3G) for answering calls. Based on the first possible implementation, it is possible to accurately determine whether a call can be made to the first terminal device through the IMS domain, which helps to avoid call failures.

[0033] In conjunction with the fourth aspect or the first possible implementation, in a second possible implementation, the fourth network device is an access and mobility management function (AMF). Execution of this method by the fourth network device can make minor changes to existing standards.

[0034] In a fifth aspect, the present application provides a call processing method, which includes: a first terminal device receives a first call request in an IP multimedia system IMS domain; the first terminal device determines that the call establishment cannot be completed in the IMS domain; the first terminal device sends a first message, which carries an identifier of the first terminal device, and the first message is used to request that the first call request be redirected to the first terminal device; the first terminal device enters the CS domain to wait for a call or the first terminal device activates long-term evolution LTE capability.

[0035] Based on the method described in the fifth aspect, when the first terminal device determines that it is impossible to call the first terminal device through the IMS domain, the first terminal device can enter the CS domain to wait for the call, and enable the network side to initiate a call to the first terminal device through the CS domain, which is conducive to avoiding call failure. And the method described in the fifth aspect is that after the first terminal device receives the first call request in the IMS domain, it locally determines that the voice call cannot be established and performs the operation of reselecting to the CS network. The execution timing of the method described in the fifth aspect is early, so it can shorten the time to establish a call and reduce the waiting time of the calling party UE. And it can avoid call failure in scenarios where the 5G network does not support VoNR, or in scenarios where the 5G network supports VoNR but the 5G network signal is poor, and the application scenarios are wide.

[0036] In a first possible implementation, before the first terminal device enters the CS domain to wait for a call, the first terminal device may also send an IMS deregistration request. Based on the first possible implementation, it can be more accurately determined that the second call request to UE-1 is sent through the CS domain.

[0037] In combination with the fifth aspect and the first possible implementation, in the second possible implementation, the specific implementation method of the first terminal device determining that the call establishment cannot be completed in the IMS domain is as follows: if the first condition is met, the first terminal device determines that the call establishment cannot be completed in the IMS domain; the first condition includes one or more combinations of the following: the long-term evolution LTE capability of the first terminal device is turned off; the 5G signal strength measured by the first terminal device is less than a threshold; when the first terminal device performs fifth-generation mobile communication technology 5G registration, it receives indication information sent by the network to indicate that calls in the IMS domain are not supported. Based on the second possible implementation, UE-1 can accurately determine that the call establishment cannot be completed in the IMS domain, which is conducive to avoiding call failures.

[0038] In combination with the second possible implementation, in a third possible implementation, the first condition also includes that the network does not support switching from NG-RAN to UTRAN.

[0039] In combination with any one of the fifth aspect, the first possible implementation, the second possible implementation, and the third possible implementation, in a fourth possible implementation, the first message carries third information, and the third information is used by the second network device to carry second information when sending a first request to the third network device; the first request is used to request that the call be routed to the first terminal device through the CS domain, and the second information is used by the third network device to send the first information to the second network device after determining that the first terminal device has completed CS domain registration or location update. Based on the fourth possible implementation, it is helpful to avoid the second network device from making a CS call to the first terminal device earlier than the CS registration completion time of the first terminal device, thereby avoiding the call failing again.

[0040] In combination with any one of the fifth aspect, the first possible implementation method, the second possible implementation method, and the third possible implementation method, in the fifth possible implementation method, the first message carries seventh information, and the seventh information is used by the second network device to carry the fifth information when sending a first request to the third network device; the first request is used to request the fourth information, and the fourth information is used to determine whether a call can be made to the first terminal device through the IMS domain; the fifth information is used by the third network device to carry the sixth information when sending a second request to the fourth network device, and the second request is used to request the fourth information, and the sixth information is used by the fourth network device to send the fourth information to the third network device after determining that the first terminal device has enabled the Long Term Evolution (LTE) capability. Based on the fifth possible implementation method, it is helpful to avoid the second network device from making an IMS call to the first terminal device earlier than the time when the first terminal device enables the LTE capability, thereby avoiding the call failing again.

[0041] In combination with any one of the fifth aspect, the first possible implementation method, the second possible implementation method, and the third possible implementation method, in a sixth possible implementation method, the first message also carries a timer, which is used for the second network device to initiate a call to the first terminal device through the CS domain or the IMS domain when the timer expires. Based on the sixth possible implementation method, it is beneficial to avoid the second network device's CS call to the first terminal device being earlier than the time when the CS registration of the first terminal device is completed, thereby avoiding the call failing again. Or it is beneficial to avoid the second network device's IMS call to the first terminal device being earlier than the time when the first terminal device turns on the LTE capability, thereby avoiding the call failing again.

[0042] In conjunction with any one of the fifth aspect, the first possible implementation, the second possible implementation, the third possible implementation, the fourth possible implementation, the fifth possible implementation, and the sixth possible implementation, in a seventh possible implementation, a specific implementation of the first terminal device entering the CS domain to wait for a call comprises: the first terminal device reselecting to a second-generation mobile communication technology (2G) network or a third-generation mobile communication technology (3G) network; the first terminal device sending an attach request or a location update request to a mobile switching center (MSC); and the first terminal device waiting for a call in the CS domain. Based on the third possible implementation, the CS domain can be successfully entered.

[0043] In combination with any one of the fifth aspect, the first possible implementation manner, the second possible implementation manner, the third possible implementation manner, the fourth possible implementation manner, the fifth possible implementation manner, the sixth possible implementation manner, and the seventh possible implementation manner, in an eighth possible implementation manner, after the first terminal device enters the CS domain to wait for a call, the first terminal device may further receive a second call request in the CS domain. Based on the fourth possible implementation manner, the first terminal device can successfully receive the call request, avoiding call failure.

[0044] In combination with any one of the fifth aspect, the first possible implementation, the second possible implementation, the third possible implementation, the fourth possible implementation, the fifth possible implementation, and the sixth possible implementation, in a ninth possible implementation, after the first terminal device enables LTE capability, the first terminal device may further send a registration request to the fourth network device, where the registration request carries the Long Term Evolution (LTE) capability; and the first terminal device may further receive a second call request in the IP Multimedia System (IMS) domain. Based on the fifth possible implementation, the latest capability information of the first terminal device can be reported to the network side in a timely manner.

[0045] In a sixth aspect, the present application provides a call processing method, the method comprising: a second network device sends a first call request to a first terminal device through an IP multimedia system IMS domain; the second network device receives a first message sent by the first terminal device, the first message carrying an identifier of the first terminal device, and the first message is used to request that the first call request be redirected to the first terminal device; the second network device sends a second call request to the first terminal device through a CS domain or an IMS domain.

[0046] The beneficial effects of the sixth aspect and possible implementation methods of the sixth aspect can be found in the beneficial effects of the fifth aspect and possible implementation methods of the fifth aspect, and will not be repeated here.

[0047] In a first possible implementation manner, before the second network device sends the second call request to the first terminal device through the CS domain, the second network device may further receive an IMS deregistration request sent by the first terminal device.

[0048] In combination with the sixth aspect or the first possible implementation method, in the second possible implementation method, the specific implementation method of the second network device sending the second call request to the first terminal device through the CS domain is: the second network device sends a first request to the third network device, and the first request is used to request that the call be routed to the first terminal device through the CS domain; the second network device receives the first information sent by the third network device; and the second network device sends the second call request to the first terminal device through the CS domain based on the first information.

[0049] In combination with the second possible implementation, in a third possible implementation, the first request carries the second information, and the third network device sends the first information to the second network device based on the second information after determining that the first terminal device completes the CS domain registration or location update.

[0050] In combination with the third possible implementation manner, in a fourth possible implementation manner, the first message carries third information, and the third information is used to carry the second information when the second network device sends the first request to the third network device.

[0051] In combination with the sixth aspect, in the fifth possible implementation method, the specific implementation method of the second network device sending the second call request to the first terminal device through the IMS domain is: the second network device sends a first request to the third network device, and the first request is used to request fourth information, and the fourth information is used to determine whether the first terminal device can be called through the IMS domain; the second network device receives the fourth information sent by the third network device; if the second network device determines that the first terminal device cannot be called through the IMS domain based on the fourth information, the second network device sends the second call request to the first terminal device through the IMS domain.

[0052] In combination with the fifth possible implementation method, in the sixth possible implementation method, the first request carries the fifth information, and the third network device may send a second request carrying the sixth information to the fourth network device based on the fifth information, and the second request is used to request the fourth information; the fourth network device may send the fourth information to the third network device based on the sixth information after determining that the first terminal device has enabled the Long Term Evolution LTE capability; the third network device may also send the fourth information to the second network device.

[0053] In combination with the sixth possible implementation manner, in a seventh possible implementation manner, the first message carries seventh information, and the seventh information is used to carry the fifth information when the second network device sends the first request to the third network device.

[0054] In combination with the second possible implementation method or the fifth possible implementation method, in the eighth possible implementation method, the first message includes a timer; the specific implementation method of the second network device sending the first request to the third network device is: when the timer expires, the second network device sends the first request to the third network device.

[0055] In a seventh aspect, the present application provides a communication device, which may be a terminal device, a device in a terminal device, or a device that can be used in conjunction with a terminal device. The communication device may also be a chip system.

[0056] The communication device can perform the method described in the first or fifth aspect. The functions of the communication device can be implemented in hardware, or the corresponding software can be implemented in hardware. The hardware or software includes one or more units or modules corresponding to the above-mentioned functions. The units or modules can be software and / or hardware. The operations and beneficial effects performed by the communication device can refer to the methods and beneficial effects described in the first or fifth aspect above, and any repetitions will not be repeated.

[0057] In an eighth aspect, the present application provides a communication device, which may be a network device, a device in a network device, or a device that can be used in conjunction with a network device. The communication device may also be a chip system. The communication device may execute the method described in the fourth aspect. The functions of the communication device may be implemented by hardware, or by hardware executing corresponding software implementations. The hardware or software includes one or more units or modules corresponding to the above functions. The unit or module may be software and / or hardware. The operations and beneficial effects performed by the communication device may refer to the method and beneficial effects described in the fourth aspect above, and repetitions will not be repeated.

[0058] In a ninth aspect, the present application provides a communication device comprising a processor, wherein when the processor calls a computer program in a memory, a method as described in any one of the first aspect, the fourth aspect, or the fifth aspect is executed.

[0059] In the tenth aspect, the present application provides a communication device, which includes a processor and a memory, and the processor and the memory are coupled; the processor is used to implement the method as described in any one of the first aspect, the fourth aspect, or the fifth aspect.

[0060] In the eleventh aspect, the present application provides a communication device, which includes a processor, a memory and a transceiver, and the processor and the memory are coupled; the transceiver is used to send and receive data, and the processor is used to implement a method as described in any one of the first aspect, the fourth aspect, or the fifth aspect.

[0061] In the twelfth aspect, the present application provides a chip, a communication device including a processor and an interface, the interface is used to receive or output signals, the interface is used to receive or output signals, and the processor is used to execute code instructions so that any one of the methods in the first aspect, the fourth aspect, or the fifth aspect is executed.

[0062] In the thirteenth aspect, the present application provides a computer-readable storage medium, which stores a computer program or instruction. When the computer program or instruction is executed by a communication device, it implements a method as described in any one of the first aspect, the fourth aspect, or the fifth aspect.

[0063] In a fourteenth aspect, the present application provides a computer program product comprising instructions, which, when a computer reads and executes the computer program product, enables the computer to perform any one of the methods in the first aspect, the fourth aspect, or the fifth aspect.

[0064] In a fifteenth aspect, the present application provides a communication system, comprising a first terminal device and a network device, wherein the first terminal device is used to execute the method described in the first aspect and any one of the possible implementations of the first aspect; the network device is used to execute the method described in the second aspect and any one of the possible implementations of the second aspect, or the network device is used to execute the method described in the third aspect and any one of the possible implementations of the third aspect, or the network device is used to execute the method described in the fourth aspect and any one of the possible implementations of the fourth aspect.

[0065] In the sixteenth aspect, the present application provides a communication system, which includes a first terminal device and a network device, wherein the first terminal device is used to execute the method described in the fifth aspect and any one of the possible implementation methods of the fifth aspect; the network device is used to execute the method described in the sixth aspect and any one of the possible implementation methods of the sixth aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Figure 1 It is a schematic diagram of a communication system;

[0067] Figure 2 This is a schematic diagram of the EPS rollback process provided in an embodiment of the present application;

[0068] Figure 3 This is a schematic diagram of the EPS rollback process provided in an embodiment of the present application;

[0069] Figures 4 to 21 A flowchart of a call processing method provided in an embodiment of the present application;

[0070] Figure 22 This is a schematic structural diagram of a communication device provided in an embodiment of the present application;

[0071] Figure 23 This is a schematic structural diagram of a communication device provided in an embodiment of the present application;

[0072] Figure 24 This is a schematic diagram of the structure of a chip provided in an embodiment of the present application. DETAILED DESCRIPTION

[0073] The specific embodiments of the present application are further described in detail below with reference to the accompanying drawings.

[0074] The terms "first" and "second" and the like in the specification, claims, and drawings of this application are used to distinguish between different objects, not to describe a particular order. Furthermore, the terms "including" and "having," and any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or elements is not limited to the listed steps or elements, but may optionally include steps or elements not listed, or may optionally include other steps or elements inherent to the process, method, product, or apparatus.

[0075] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0076] In this application, "at least one (item)" refers to one or more, "more than one" refers to two or more, "at least two (items)" refers to two or three and more than three, and "and / or" is used to describe the corresponding relationship of associated objects, indicating that there can be three relationships. For example, "A and / or B" can mean: only A exists, only B exists, and A and B exist at the same time, where A and B can be singular or plural. The character " / " generally indicates that the previous and next associated objects are in an "or" relationship. "At least one of the following items" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, at least one of a, b or c can mean: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, c can be single or multiple.

[0077] In order to better understand this application, the following describes a system architecture provided by this application:

[0078] See Figure 1 , Figure 1 This is a schematic diagram of a system architecture provided by an embodiment of the present application. Figure 1 As shown, the system architecture includes:

[0079] 1. E-UTRAN: evolved UMTS terrestrial radio access network. E-UTRAN includes multiple fourth-generation mobile communication technologies (4 th Generation (4G) access network equipment. Access network equipment is the node or device that connects terminal devices to the wireless network. Access network equipment can also be called a base station. For example, 4G access network equipment can be an evolved node B (eNB).

[0080] 2. MME: Mobile Management Entity. The MME is a 4G core network entity responsible for UE authentication, authorization, mobility management, and session management. It also assigns the LBI, the identifier for the UE's connection to the 4G public data network (PDN).

[0081] 3. SGW: Serving gateway. SGW is a 4G gateway responsible for data forwarding and downlink data storage.

[0082] 4. PGW-C: PDN gateway control plane function. PGW-C is a 4G gateway that acts as the interface between the carrier network and external networks. It is responsible for allocating IP addresses to UEs.

[0083] 5. PGW-U: PDN gateway user plane function. PGW-U is a 4G gateway and serves as the interface gateway between the carrier network and external networks.

[0084] 6. HSS: Home Subscriber Server. HSS is a 4G core network element used to store user subscription data.

[0085] 7. UDM: unified data management. UDM is a 5G core network element used to store user subscription data. Figure 1 In the example, UDM+HSS means that the UDM and HSS are deployed on one device. In the embodiment of the present application, the UDM and HSS can also be deployed separately. UDM+HSS can also be referred to as HSS+UDM.

[0086] 8. PCF: Policy Control Function. PCF is a 5G core network element responsible for generating policies for establishing data channels for users.

[0087] 9. SMF: Session Management Function. The SMF is a 5G core network element responsible for managing 5G PDU sessions. For example, it is used to establish, modify, and release sessions. The SMF is also used to manage the Quality of Service (QoS) flow used by data within 5G and is responsible for allocating IP addresses to UEs. Figure 1 In the example, "SMF+PGW-C" means that the SMF and PGW-C are deployed on one device. In the embodiment of the present application, the SMF and PGW-C can also be deployed separately. The SMF+PGW-C can also be referred to as PGW-C+SMF.

[0088] 10. UPF: User plane function. UPF is a 5G gateway that serves as the interface between the carrier network and external networks. Figure 1 In the example, "UPF+PGW-U" means that the UPF and PGW-U are deployed on one device. In the embodiment of the present application, the UPF and PGW-U can also be deployed separately. The UPF+PGW-U can also be referred to as PGW-U+UPF.

[0089] 11. AMF: Access and mobility management function. AMF is a 5G core network element used to authenticate and authorize users and manage their mobility.

[0090] 12. NG-RAN: Next-generation radio access network. NG-RAN connects devices to wireless networks. NG-RAN includes multiple 5G access network devices. For example, 5G access network devices can be next-generation base stations (gNBs).

[0091] 13. P-CSCF: Proxy CSCF, proxy call session control function. The P-CSCF is a network element in the IP multimedia subsystem (IMS) network and serves as the unified entry point to the IMS network. All session messages originating from and terminating at IMS terminals must pass through the P-CSCF.

[0092] Currently, operators' VoLTE (voice over LTE) or VoNR use the IMS (IP Multimedia Sub-system) network for signaling or session control. IMS is a service network based on IP switching. IMS supports UEs to access the IMS network through various packet switching access networks (such as 5G or 4G networks) to perform IMS multimedia services (such as voice services, video services, information services, etc.). IMS introduces the SIP (Session Initiation Protocol) protocol as a service control protocol, and uses the simplicity, easy scalability, and convenient media combination of SIP to provide rich multimedia services by separating service control from bearer control. The core of IMS is various call session control functions (CSCF) and various application servers (AS).

[0093] 14. S-CSCF: Serving CSCF, serving call session control function. The S-CSCF is an IMS network element and plays a central role in IMS network session control. It accepts registration requests forwarded from the visited network via the P-CSCF and works with the HSS (Home Subscriber Server) or UDM to authenticate users. It also downloads the user's subscribed service data from the HSS or UDM. The S-CSCF manages routing for both the calling and called sides, routing messages to the AS based on the user's subscription.

[0094] 15. AS: Application server. An AS is an IMS network element and the top-level application layer device in the IMS system. It provides basic and supplementary services, multimedia conferencing, converged communications, SMS gateways, and standard attendant consoles. For example, an AS can be a service centralization and continuity application server (SCCAS) or a telephony application server (TAS).

[0095] 16. UE: User equipment, also known as terminal device. UE includes devices that provide voice and / or data connectivity to users, and may include, for example, a handheld device with wireless connectivity or a processing device connected to a wireless modem. UE can communicate with the core network via the radio access network (RAN) and exchange voice and / or data with the RAN. UE may include wireless terminal devices, mobile terminal devices, device-to-device (D2D) terminal devices, vehicle-to-everything (V2X) terminal devices, machine-to-machine / machine-type communications (M2M / MTC) terminal devices, Internet of Things (IoT) terminal devices, subscriber units, subscriber stations, mobile stations, remote stations, access points (APs), remote terminals, access terminals, user terminals, user agents, or user equipment. For example, it may include mobile phones (also known as "cellular" phones), computers with mobile terminal devices, portable, pocket-sized, handheld, or mobile devices with built-in computers, etc. For example, personal communication service (PCS) phones, cordless phones, session initiation protocol (SIP) phones, wireless local loop (WLL) stations, personal digital assistants (PDAs), and other devices.

[0096] In the embodiments of the present application, the device for realizing the function of the terminal device can be a terminal device, or a device that can support the terminal device to realize the function, such as a chip system or a combination device or component that can realize the function of the terminal device, and the device can be installed in the terminal device. In the embodiments of the present application, the chip system can be composed of chips, or it can include chips and other discrete devices. In the technical solutions provided in the embodiments of the present application, the technical solutions provided in the embodiments of the present application are described by taking the terminal device as an example in which the device for realizing the function of the terminal is a terminal device.

[0097] To facilitate understanding of the call processing method provided in the embodiment of the present application, the EPS fallback process is first introduced below. Figure 2 As shown, the EPS fallback process includes the following sections 201 to 207, where:

[0098] 201. UE-1 receives an invite message from the IMS network. UE-1 negotiates voice services with its counterpart, UE-2, via the IMS network. After the negotiation is complete, the IMS network sends a request to the SMF+PGW-C for establishing a voice data channel.

[0099] UE-1 receives an invite message sent by the IMS network, indicating that UE-1 is the called party. Correspondingly, UE-2 is the caller and sends an invite message via the IMS network.

[0100] 202. SMF+PGW-C sends a PDU session modification request to NG-RAN to establish a voice data channel.

[0101] Specifically, after SMF+PGW-C receives the request sent by the IMS network to establish a voice data channel, it sends a PDU session modification request to NG-RAN.

[0102] 203. NG-RAN determines whether a voice data channel can be established in the 5G network.

[0103] Specifically, after receiving the PDU session modification request, NG-RAN determines whether a voice data channel can be established in the 5G network.

[0104] NG-RAN determines whether a voice data channel can be established on a 5G network in the following two situations:

[0105] Case 1: If the 5G network does not support VoNR, NG-RAN directly determines that it cannot establish a voice data channel on the 5G network.

[0106] Case 2: If the 5G network supports VoNR, the NG-RAN initiates a measurement configuration to UE-1, instructing UE-1 to measure the 5G network signal strength. Based on the 5G network signal strength measurement results reported by UE-1, the NG-RAN determines whether a voice and data channel can be established on the 5G network. For example, if the NG-RAN determines that the UE-1's current signal strength is less than a preset value, the NG-RAN determines that a voice and data channel cannot be established on the 5G network. If the NG-RAN determines that the UE's current signal strength is greater than a preset value, the NG-RAN determines that a voice and data channel can be established on the 5G network.

[0107] 204. After determining that the voice data channel cannot be established in the 5G network, NG-RAN sends a rejection message to SMF+PGW-C. The rejection message is used by SMF+PGW-C to determine that the fallback process is being executed to establish the voice data channel.

[0108] 205. NG-RAN initiates a process of handing over or redirecting UE-1 to 4G.

[0109] 206. After UE-1 switches or redirects to 4G, it initiates a tracking area update (TAU) process in the 4G network.

[0110] 207. The SMF+PGW-C establishes a voice data channel in the 4G network through a PDN connection modification message.

[0111] For 5G communication systems, the data channel refers to QoS flow; for 4G communication systems, the data channel refers to EPS bearer. For 5G communication systems, the voice data channel refers to the QoS flow with a 5QI (5G quality identity) value of 1. For 4G communication systems, the voice data channel refers to the EPS bearer with a QCI (QoS class identifier) ​​value of 1. 5QI is a parameter of QoS flow, which is used to identify the service level or service characteristics that the QoS flow can provide. QCI is a parameter of EPS bearer, which is used to identify the service level or service characteristics that the EPS bearer can provide.

[0112] Figure 3 The process shown is the specific process of step 201. Among them:

[0113] 301. UE-2 sends an invite message to S-CSCF-2 that provides services for UE-2.

[0114] The invite message includes information such as the address of UE-1 and the voice codec supported by UE-2. The invite message is sent to S-CSCF-2 via P-CSCF-2 that provides service for UE-2.

[0115] 302. S-CSCF-2 sends the invite message to S-CSCF-1 that provides service for UE-1 according to the address of UE-1.

[0116] Before sending the invite message to S-CSCF-1, S-CSCF-2 may send the invite message to AS-2 that provides services for UE-2. After processing, AS-2 sends the invite message to S-CSCF-2.

[0117] 303. S-CSCF-1 sends the invite message to AS-1 that provides services for UE-1.

[0118] 304. AS-1 queries the UDM+HSS for availability of calling UE-1 in the IMS domain.

[0119] 305. The UDM+HSS queries the AMF for the availability of calling UE-1 in the IMS domain.

[0120] 306. The AMF feeds back the confirmation result to the UDM+HSS.

[0121] If IMS domain calling is available, the system will reply to the UDM+HSS that "IMS voice over PS supported" is supported. Otherwise, the system will reply that "IMS voice over PS not supported" is supported.

[0122] 307. UDM+HSS feeds back the results to AS-1.

[0123] 308. If IMS domain calling is available, AS-1 sends an invite message to S-CSCF-1.

[0124] 309. S-CSCF-1 sends an invite message to UE-1.

[0125] The invite message is sent to UE-1 through P-CSCF-1 that provides service for UE-1.

[0126] 310. After receiving the invite message, UE-1 replies with a 183 message to UE2.

[0127] The 183 message carries the codec selected by UE-1 from the codecs carried in the invite message, thereby determining the codec used for this voice call. For example, UE-2 provides three coding methods, UE-1 selects one and replies to UE-2 via the 183 message. Figure 3 As shown, the 183 message passes through P-CSCF-1, S-CSCF-1, AS-1, S-CSCF-1, S-CSCF-2 and UE-2 in sequence.

[0128] 311. Based on the negotiation result between UE-1 and UE-2, P-CSCF-1 sends a request for establishing a voice data channel to SMF+PGW-C through PCF.

[0129] The following is a detailed description of the call processing method and communication device provided by this application:

[0130] See Figure 4 , Figure 4 The present invention provides a flowchart of a call processing method provided in an embodiment of the present invention. The call processing method involves a first terminal device, a first network device, and a second network device. Figure 4 Take the first terminal device as UE-1, the first network device as P-CSCF-1, and the second network device as AS-1 as an example. The first network device and the second network device may also be other network devices, which are not limited in the embodiment of the present application. For example, the first network device may be other IMS network elements, and the second network device may also be S-CSCF-1. Among them, P-CSCF-1, S-CSCF-1 and AS-1 are IMS network elements used to serve the first terminal device. Figure 4 As shown, the call processing method includes the following parts 401 to 406. Among them:

[0131] 401. AS-1 sends a first call request to UE-1 via the IMS domain. Correspondingly, UE-1 may receive the first call request in the IMS domain.

[0132] In this embodiment of the present application, UE-2 is the calling end and UE-1 is the called end. UE-1 resides on a 5G network, and UE-1's LTE capability is disabled (i.e., its S1 mode is disabled). The IMS domain is used to place calls to UEs residing on 4G or 5G networks. When UE-2 calls UE-1, it can send a first call request to UE-1 via the IMS domain.

[0133] For details, see the process of UE-2 sending the first call request to UE-1 through the IMS domain. Figure 3 The corresponding process. Among them, the first call request can be Figure 3Before AS-1 sends the first call request to UE-1 through the IP Multimedia System IMS domain, it may also include Figure 3 The implementation method of AS-1 sending the first call request to UE-1 through the IP Multimedia System IMS domain may include: Figure 3 Steps 304 to 309 in .

[0134] In the embodiment of the present application, AS-1 may be an SCC AS or a TAS. AS-1 in the subsequent embodiments is the same as that in the present embodiment and will not be described in detail.

[0135] 402. P-CSCF-1 receives second information. The second information is used by P-CSCF-1 to determine that a voice data channel cannot be established for UE-1.

[0136] Optionally, the P-CSCF-1 may receive the second information sent by the SMF+PGW-C. The SMF+PGW-C may also be referred to as the SMF or PGW-C. Alternatively, the P-CSCF-1 may receive the second information sent by another network element, for example, a network element with similar functions to the SMF in a 6G or later network. In the embodiment of the present application, the example of the P-CSCF-1 receiving the second information sent by the SMF+PGW-C is taken as an example.

[0137] Combine Figure 2 and Figure 3 As shown, after UE-1 receives the first call request (i.e., invite message) in the IMS domain, P-CSCF-1 sends a request to SMF+PGW-C for establishing a voice data channel. After receiving the request for establishing the voice data channel, SMF+PGW-C sends a PDU session modification request to NG-RAN to establish the voice data channel. After receiving the PDU session modification request, NG-RAN determines whether a voice data channel can be established in the 5G network. NG-RAN determines that a voice data channel cannot be established in the 5G network based on the fact that the 5G network does not support VoNR; or, NG-RAN determines that a voice data channel cannot be established in the 5G network based on the 5G network signal measurement report reported by the UE, that is, the 5G network signal strength is less than the threshold.

[0138] Because UE-1's LTE capability is disabled, the AMF notifies the NG-RAN that UE-1 cannot fall back to 4G to perform voice services (Redirection for EPS fallback for voice is not possible) when UE-1 enters the connected state from the idle state. After the NG-RAN determines that it cannot establish a voice data channel in the 5G network, it cannot perform the EPS fallback process because the LTE capability of UE-1 is disabled. The NG-RAN determines that it cannot establish a voice data channel for UE-1. In other words, a voice data channel cannot be established for UE-1 in both the 5G and 4G networks. Therefore, the NG-RAN sends target information to the SMF+PGW-C for the SMF+PGW-C to determine that the voice data channel cannot be established for UE-1. After receiving the target information, the SMF+PGW-C sends a second information to the P-CSCF-1. The second information is used by the P-CSCF-1 to determine that the voice data channel cannot be established for UE-1. The target information and the second information may be the same or different.

[0139] 403. P-CSCF-1 sends third information to AS-1, where the third information is used by AS-1 to determine whether to call UE-1 through the CS domain. Accordingly, AS-1 may receive the third information.

[0140] In the embodiment of the present application, after receiving the second information, P-CSCF-1 sends the third information to AS-1. P-CSCF-1 may first send the third information to S-CSCF-1, and then S-CSCF-1 sends the third information to AS-1.

[0141] The CS domain is a domain or network within the 2G / 3G network specifically used for voice calls. Since UE-1 cannot establish a voice and data channel on the 5G network and its LTE capability is disabled, UE-1 cannot fall back to the 4G network. In this embodiment, UE-1 can enter the CS domain to receive the call, that is, reselect to the 2G / 3G network to receive the call. Accordingly, AS-1 can send a second call request to UE-1 via the CS domain, i.e., a second call request.

[0142] In one possible implementation, the second information is also used by P-CSCF-1 to determine whether UE-1's LTE capabilities have been disabled. The third information is also used by AS-1 to determine whether UE-1's LTE capabilities have been disabled. By notifying P-CSCF-1 that UE-1's LTE capabilities have been disabled, P-CSCF-1 can accurately determine whether it is necessary to call UE-1 again in the CS domain, avoiding terminating the call upon receiving information indicating that a voice or data channel cannot be established for UE-1. Notifying AS-1 that UE-1's LTE capabilities have been disabled informs AS-1 of the reason for calling UE-1 again in the CS domain.

[0143] Optionally, the second information may include two fields, one field for P-CSCF-1 to determine that a voice and data channel cannot be established for UE-1. The other field is used by P-CSCF-1 to determine that UE-1's LTE capability is disabled. Alternatively, the second information may include a field for P-CSCF-1 to determine that a voice and data channel cannot be established for UE-1 and to determine that UE-1's LTE capability is disabled.

[0144] Optionally, the third information may include two fields, one field for AS-1 to determine that a voice and data channel cannot be established for UE-1. The other field is used by AS-1 to determine that the LTE capability of UE-1 is disabled. Alternatively, the third information may include a field for AS-1 to determine that a voice and data channel cannot be established for UE-1 and to determine that the LTE capability of UE-1 is disabled.

[0145] 404. P-CSCF-1 sends first information to UE-1, where the first information is used by UE-1 to determine that it is entering the CS domain to wait for a call. Accordingly, UE-1 may receive the first information.

[0146] In the embodiment of the present application, after receiving the second information, P-CSCF-1 sends the first information to UE-1.

[0147] 405. AS-1 sends a second call request to UE-1 through the CS domain.

[0148] In the embodiment of the present application, after receiving the third information, AS-1 sends a second call request to UE-1 via the CS domain. The second call request may also be referred to as an invite message.

[0149] 406. UE-1 enters the CS domain and waits for a call.

[0150] In the embodiment of the present application, after UE-1 receives the first information, UE-1 enters the CS domain and waits for a call.

[0151] In another possible implementation, when UE-1 resides on a first network (the first network is a 6G network or a network after 6G), if a call to UE-1 cannot be successfully made through the domain corresponding to the first network, the first information can also be used by UE-1 to determine whether to enter the domain corresponding to the second network (the second network is a network of the previous generation of the first network) (such as the IMS domain corresponding to the 5G network) to wait for the call. Accordingly, based on the first information, UE-1 enters the domain corresponding to the second network to wait for the call. The third information is used by AS-1 to determine whether to call UE-1 through the domain corresponding to the second network.

[0152] It can be seen that based on Figure 4 The described method can enable AS-1 to send a call to UE-1 through the CS domain when the 5G network cannot establish a voice and data channel and the LTE capability of UE-1 is disabled, and enable UE-1 to enter the CS domain to wait for the call, which is helpful to avoid call failure. Figure 4 The described method can avoid call failures in scenarios where the 5G network does not support VoNR, or in scenarios where the 5G network supports VoNR but the 5G network signal is poor, and has a wide range of application scenarios.

[0153] See Figure 5 , Figure 5 The present invention provides a flowchart of a call processing method provided by an embodiment of the present invention. The call processing method involves a first terminal device, a first network device, a second network device, and a third network device. Figure 5 Take the first terminal device as UE-1, the first network device as P-CSCF-1, the second network device as AS-1, and the third network device as UDM+HSS as an example. Of course, the first network device, the second network device, and the third network device can also be other network devices, which are not limited in this embodiment of the application. The third network device can also be UDM or HSS, or a network element used to store user subscription data in a 6G or later network. Figure 5 As shown, the call processing method includes the following parts 501 to 508. Among them:

[0154] 501. AS-1 sends a first call request to UE-1 via the IMS domain. Correspondingly, UE-1 may receive the first call request in the IMS domain.

[0155] 502. P-CSCF-1 receives second information. The second information is used by P-CSCF-1 to determine that a voice data channel cannot be established for UE-1.

[0156] 503. P-CSCF-1 sends third information to AS-1, where the third information is used by AS-1 to determine whether to call UE-1 through the CS domain. Accordingly, AS-1 may receive the third information.

[0157] 504. P-CSCF-1 sends first information to UE-1, where the first information is used by UE-1 to determine that it is entering the CS domain to wait for a call. Accordingly, UE-1 may receive the first information.

[0158] 505. UE-1 enters the CS domain and waits for a call.

[0159] The description of steps 501 to 505 can be found in Figure 4 The description in the corresponding embodiments will not be repeated here.

[0160] 506. AS-1 sends a first request to the UDM+HSS, where the first request is used to request that the call be routed to the fourth information of UE-1 through the CS domain. Accordingly, the UDM+HSS may receive the first request.

[0161] In the embodiment of the present application, after receiving the third information, AS-1 sends a first request to the UDM+HSS.

[0162] Optionally, the fourth information may be a CS domain routing number (CS domain Routing Number, CSRN), or may be other routing information.

[0163] 507. The UDM+HSS sends the fourth information to AS-1. Accordingly, AS-1 may receive the fourth information.

[0164] In the embodiment of the present application, after receiving the first request, the UDM+HSS sends the fourth information to AS-1.

[0165] 508. AS-1 sends a second call request to UE-1 through the CS domain based on the fourth information.

[0166] Specifically, AS-1 may send the fourth information and the second call request to S-CSCF-1, and S-CSCF-1 may send the second call request to UE-1 via the CS domain based on the fourth information. For a detailed description of S-CSCF-1 sending the second call request to UE-1 via the CS domain based on the fourth information, see Figure 6 The description in the corresponding embodiment is not repeated here.

[0167] It can be seen that based on Figure 5 According to the described method, AS-1 can obtain the fourth information for routing the call to UE-1 through the CS domain, and send a second call request to UE-1 based on the fourth information, so that the call can be accurately routed to UE-1.

[0168] See Figure 6 , Figure 6This is a flowchart of a call processing method provided by an embodiment of the present application. The call processing method involves a first terminal device, a first network device, a second network device, a third network device, and a fifth network device. Figure 6 For example, the first terminal device is UE-1, the first network device is P-CSCF-1, the second network device is AS-1, the third network device is UDM+HSS, and the fifth network device is MSC. Figure 6 As shown, the call processing method includes the following parts 601 to 612. Among them:

[0169] 601. AS-1 sends a first call request to UE-1 via the IMS domain. Correspondingly, UE-1 may receive the first call request in the IMS domain.

[0170] 602. P-CSCF-1 receives second information. The second information is used by P-CSCF-1 to determine that a voice data channel cannot be established for UE-1.

[0171] 603. P-CSCF-1 sends third information to AS-1. The third information is used by AS-1 to determine to call UE-1 through the CS domain. Accordingly, AS-1 may receive the third information.

[0172] 604. P-CSCF-1 sends first information to UE-1, where the first information is used by UE-1 to determine that it is entering the CS domain to wait for a call. Accordingly, UE-1 may receive the first information.

[0173] The description of steps 601 to 604 can be found in Figure 4 The description in the corresponding embodiments will not be repeated here.

[0174] 605. UE-1 reselects to the 2G network or the 3G network.

[0175] In the embodiment of the present application, after UE-1 receives the first information, UE-1 reselects to the 2G network or the 3G network.

[0176] 606. UE-1 sends an attach request or a location update request to the MSC. Correspondingly, the MSC may receive the attach request or the location update request.

[0177] In the embodiment of the present application, after UE-1 reselects to the 2G network or 3G network, it sends an attach request or a location update request to the MSC. After UE-1 successfully sends the attach request or the location update request, it indicates that UE-1 has entered the CS domain.

[0178] 607. UE-1 waits for a call in the CS domain.

[0179] 608. The MSC sends a request for updating the location of UE-1 to the UDM+HSS. Correspondingly, the UDM+HSS may receive the request for updating the location of UE-1.

[0180] In this embodiment of the present application, after receiving the attach request or location update request sent by UE-1, the MSC sends a request to the UDM+HSS to update the location of UE-1. Thus, after receiving the request to update the location of UE-1, the UDM+HSS can determine that UE-1 has completed the CS domain registration or location update.

[0181] 609. AS-1 sends a first request to the UDM+HSS, where the first request is used to request that the call be routed to the fourth information of UE-1 through the CS domain, and the first request carries the fifth information. Accordingly, the UDM+HSS may receive the first request.

[0182] The fifth information is used by the UDM+HSS to send the fourth information to the AS-1 after determining that the UE-1 completes the CS domain registration or location update.

[0183] 610. After determining that UE-1 has completed CS domain registration or location update based on the fifth information, the UDM+HSS sends the fourth information to AS-1. Accordingly, AS-1 may receive the fourth information.

[0184] In this embodiment of the present application, after the UDM+HSS receives the request from the MSC to update UE-1's location, it determines that UE-1 has completed CS domain registration or location update. UE-1's completion of CS domain registration or location update indicates that UE-1 has successfully entered the CS domain. By sending the fourth information to AS-1 only after determining that UE-1 has completed CS domain registration or location update, AS-1 can prevent the CS call to UE-1 from being initiated before UE-1's CS registration is completed, thereby preventing further call failure.

[0185] In another possible implementation, the first request may not carry the fifth information. The protocol may stipulate that the UDM+HSS sends the fourth information to AS-1 after determining that UE-1 completes CS domain registration or location update.

[0186] 611. AS-1 sends a second call request to UE-1 through the CS domain based on the fourth information.

[0187] In an embodiment of the present application, after AS-1 receives the fourth information sent by UDM+HSS, it sends a second call request to UE-1 through the CS domain based on the fourth information. AS-1 may first send the second call request to S-CSCF-1. S-CSCF-1 sends the second call request through the CS domain. S-CSCF-1 may route the second call request to the MSC (Mobile Switching Center) providing services for UE-1 through the boundary network elements BGCF (Breakout Gateway Control Function) and MGCF (Media Gateway Control Function) between the IMS and CS domains. Among them, MGCF maps the second call request into a call message IAM (initial address message) of the CS domain and sends it to the MSC.

[0188] If the second network device is S-CSCF-1, S-CSCF-1 can directly route the second call request to the MSC serving UE-1 through the BGCF and MGCF, the border network elements between the IMS and CS domains. The MGCF maps the second call request into a CS domain call message IAM and sends it to the MSC.

[0189] 612. The MSC sends a call request to UE-1. Correspondingly, UE-1 receives the call request in the CS domain.

[0190] In the embodiment of the present application, after receiving the IAM, the MSC sends a call request to UE-1 based on the IAM. The call request may be called a CS setup message.

[0191] See Figure 7 , Figure 7 The present invention provides a flowchart of a call processing method provided by an embodiment of the present invention. The call processing method involves a first terminal device, a first network device, a second network device, and a third network device. Figure 7 For example, the first terminal device is UE-1, the first network device is P-CSCF-1, the second network device is AS-1, and the third network device is UDM+HSS. Figure 7 As shown, the call processing method includes the following parts 701 to 708. Among them:

[0192] 701. AS-1 sends a first call request to UE-1 via the IMS domain. Correspondingly, UE-1 may receive the first call request in the IMS domain.

[0193] 702. P-CSCF-1 receives second information. The second information is used by P-CSCF-1 to determine that a voice data channel cannot be established for UE-1.

[0194] 703. P-CSCF-1 sends third information to AS-1. The third information is used by AS-1 to determine to call UE-1 through the CS domain. The third information also includes a timer. Accordingly, AS-1 may receive the third information.

[0195] This timer is used by AS-1 to initiate a call to UE-1 via the CS domain when the timer expires. This timer is also called a delay timer.

[0196] 704. P-CSCF-1 sends first information to UE-1, where the first information is used by UE-1 to determine that it is entering the CS domain to wait for a call. Accordingly, UE-1 may receive the first information.

[0197] 705. UE-1 enters the CS domain and waits for a call.

[0198] For further description of steps 701 to 705, please refer to Figure 4 The description in the corresponding embodiments will not be repeated here.

[0199] 706. When the timer expires, AS-1 sends a first request to the UDM+HSS, where the first request is used to request that the call be routed to the fourth information of UE-1 through the CS domain. Accordingly, the UDM+HSS may receive the first request.

[0200] When the timer expires, AS-1 sends a first request to the UDM+HSS. This helps prevent AS-1 from making a CS call to UE-1 before UE-1's CS registration is completed, thus causing the call to fail again.

[0201] In another possible implementation, the third information may not include a timer. The timer may be predefined by a protocol.

[0202] 707. The UDM+HSS sends the fourth information to AS-1. Accordingly, AS-1 may receive the fourth information.

[0203] 708. AS-1 sends a second call request to UE-1 through the CS domain based on the fourth information.

[0204] For other descriptions of steps 706 to 708, please refer to Figure 5 The description in the corresponding embodiment is not repeated here.

[0205] See Figure 8 , Figure 8The present invention provides a flowchart of a call processing method provided in an embodiment of the present invention. The call processing method involves a first terminal device, a first network device, and a second network device. Figure 8 For example, the first terminal device is UE-1, the first network device is P-CSCF-1, and the second network device is AS-1. Figure 8 As shown, the call processing method includes the following parts 801 to 806. Among them:

[0206] 801. AS-1 sends a first call request to UE-1 via the IMS domain. Correspondingly, UE-1 may receive the first call request in the IMS domain.

[0207] 802. P-CSCF-1 receives second information. The second information is used by P-CSCF-1 to determine that a voice data channel cannot be established for UE-1.

[0208] For the description of step 801 and step 802, please refer to the description of step 401 and step 402 in the previous text, which will not be repeated here.

[0209] 803. P-CSCF-1 sends third information to AS-1. The third information is used by AS-1 to determine to call UE-1 through the IMS domain. Accordingly, AS-1 may receive the third information.

[0210] In the embodiment of the present application, after receiving the second information, P-CSCF-1 sends third information to AS-1.

[0211] In a possible implementation, the second information is further used by P-CSCF-1 to determine that the LTE capability of UE-1 is disabled. The third information is further used by AS-1 to determine that the LTE capability of UE-1 is disabled.

[0212] Optionally, the second information may include two fields, one field for P-CSCF-1 to determine that a voice and data channel cannot be established for UE-1. The other field is used by P-CSCF-1 to determine that UE-1's LTE capability is disabled. Alternatively, the second information may include a field for P-CSCF-1 to determine that a voice and data channel cannot be established for UE-1 and to determine that UE-1's LTE capability is disabled.

[0213] Optionally, the third information may include two fields, one field for AS-1 to determine that a voice and data channel cannot be established for UE-1. The other field is used by AS-1 to determine that the LTE capability of UE-1 is disabled. Alternatively, the third information may include a field for AS-1 to determine that a voice and data channel cannot be established for UE-1 and to determine that the LTE capability of UE-1 is disabled.

[0214] 804. P-CSCF-1 sends first information to UE-1, where the first information is used by UE-1 to determine whether to enable LTE capability. Accordingly, UE-1 may receive the first information.

[0215] In the embodiment of the present application, after receiving the second information, P-CSCF-1 sends the first information to UE-1.

[0216] 805. UE-1 enables LTE capability.

[0217] In the embodiment of the present application, after receiving the first information, UE-1 turns on the LTE capability, so that it can wait to be called again in the IMS domain.

[0218] 806. AS-1 sends a second call request to UE-1 via the IMS domain. Correspondingly, UE-1 may receive the second call request in the IMS domain.

[0219] In the embodiment of the present application, after receiving the third information, AS-1 sends a second call request to UE-1 through the IMS domain. The second call request may be called an invite message.

[0220] It can be seen that based on Figure 8 The described method can enable UE-1 to enable LTE capability when the 5G network cannot establish a voice data channel and UE-1's LTE capability is disabled, and enable AS-1 to resend the call to UE-1 through the IMS domain, which is helpful to avoid call failure. Figure 8 The described method can avoid call failures in scenarios where the 5G network does not support VoNR, or in scenarios where the 5G network supports VoNR but the 5G network signal is poor, and has a wider range of application scenarios.

[0221] See Figure 9 , Figure 9 This is a flowchart of a call processing method provided by an embodiment of the present application. The call processing method involves a first terminal device, a first network device, a second network device, a third network device, and a fourth network device. Figure 9 For example, the first terminal device is UE-1, the first network device is P-CSCF-1, the second network device is AS-1, the third network device is UDM+HSS, and the fourth network device is AMF. Figure 9 As shown, the call processing method includes the following parts 901 to 911. Among them:

[0222] 901. AS-1 sends a first call request to UE-1 via the IMS domain. Correspondingly, UE-1 may receive the first call request in the IMS domain.

[0223] 902. P-CSCF-1 receives second information. The second information is used by P-CSCF-1 to determine that a voice data channel cannot be established for UE-1.

[0224] 903. P-CSCF-1 sends third information to AS-1. The third information is used by AS-1 to determine to call UE-1 through the IMS domain. Accordingly, AS-1 may receive the third information.

[0225] 904. P-CSCF-1 sends first information to UE-1, where the first information is used by UE-1 to determine whether to enable LTE capability. Accordingly, UE-1 may receive the first information.

[0226] 905. UE-1 enables LTE capability.

[0227] The detailed description of steps 901 to 905 can be found in Figure 8 The description in the corresponding embodiment is not repeated here.

[0228] 906. UE-1 sends a registration request to the AMF. The registration request carries UE-1's LTE capability information. Accordingly, the AMF may receive the registration request.

[0229] In this embodiment of the present application, after UE-1 enables LTE capabilities, it sends a registration request to the AMF. Therefore, by executing step 906, UE-1 can promptly report its capability information to the AMF so that the AMF can promptly determine the latest capability information of UE-1.

[0230] Optionally, the AMF may also send UE-1's LTE capability information to the NG-RAN.

[0231] 907. AS-1 sends a first request to the UDM+HSS, where the first request is used to request sixth information, where the sixth information is used to determine whether a call can be made to UE-1 through the IMS domain. Accordingly, the UDM+HSS may receive the first request.

[0232] In the embodiment of the present application, after receiving the third information, AS-1 sends a first request to the UDM+HSS. Step 906 can be understood as AS-1 initiating a call to UE-1 through the IMS domain.

[0233] 908. The UDM+HSS sends a second request to the AMF, where the second request is for requesting the sixth information. Accordingly, the AMF may receive the second request.

[0234] In this embodiment of the present application, after receiving the first request, UDM+HSS sends a second request to AMF.

[0235] 909. The AMF sends the sixth information to the UDM+HSS. Correspondingly, the UDM+HSS may receive the sixth information.

[0236] In this embodiment of the present application, after receiving the second request, the AMF determines whether a call can be made to UE-1 through the IMS domain. If the AMF determines that a call can be made to UE-1 through the IMS domain, the sixth information is used by AS-1 to determine that a call can be made to UE-1 through the IMS domain. If the AMF determines that a call cannot be made to UE-1 through the IMS domain, the sixth information is used by AS-1 to determine that a call cannot be made to UE-1 through the IMS domain.

[0237] Optionally, the AMF may determine whether a call can be made to UE-1 via the IMS domain based on the capability information of UE-1 and / or the capability information of the network. For example, when the network supports VoNR, the AMF may determine that a call can be made to UE-1 via the IMS domain. When the network does not support VoNR, the network supports EPS fallback, and UE-1 has LTE capability, the AMF may determine that a call can be made to UE-1 via the IMS domain.

[0238] 910. The UDM+HSS sends the sixth information to AS-1. Accordingly, AS-1 may receive the sixth information.

[0239] 911. If AS-1 determines based on the sixth information that a call can be made to UE-1 through the IMS domain, AS-1 sends a second call request to UE-1 through the IMS domain. Accordingly, UE-1 may receive the second call request in the IMS domain.

[0240] By executing steps 907 to 911 , AS- 1 can query other network devices whether it is currently possible to use the IMS domain to call UE- 1 , thereby avoiding further call failures through the IMS domain.

[0241] See Figure 10 , Figure 10 This is a flowchart of a call processing method provided by an embodiment of the present application. The call processing method involves a first terminal device, a first network device, a second network device, a third network device, and a fourth network device. Figure 10 For example, the first terminal device is UE-1, the first network device is P-CSCF-1, the second network device is AS-1, the third network device is UDM+HSS, and the fourth network device is AMF. Figure 10 As shown, the call processing method includes the following parts 1001 to 1011. Among them:

[0242] 1001. AS-1 sends a first call request to UE-1 via the IMS domain. Correspondingly, UE-1 may receive the first call request in the IMS domain.

[0243] 1002. P-CSCF-1 receives second information. The second information is used by P-CSCF-1 to determine that a voice data channel cannot be established for UE-1.

[0244] 1003. P-CSCF-1 sends third information to AS-1. The third information is used by AS-1 to determine to call UE-1 through the IMS domain. Accordingly, AS-1 may receive the third information.

[0245] 1004. P-CSCF-1 sends first information to UE-1, where the first information is used by UE-1 to determine whether to enable LTE capability. Accordingly, UE-1 may receive the first information.

[0246] 1005. UE-1 enables LTE capability.

[0247] 1006. UE-1 sends a registration request to the AMF. The registration request carries UE-1's LTE capability information. Accordingly, the AMF may receive the registration request.

[0248] The detailed description of steps 1001 to 1006 can be found in Figure 8 The description in the corresponding embodiment is not repeated here.

[0249] 1007. AS-1 sends a first request carrying seventh information to the UDM+HSS, where the first request is used to request sixth information used to determine whether a call can be made to UE-1 through the IMS domain. Accordingly, the UDM+HSS may receive the first request.

[0250] The seventh information is used by the UDM+HSS to carry the eighth information when sending the second request to the AMF. The eighth information is used by the AMF to send the sixth information to the UDM+HSS after determining that UE-1 has enabled LTE capability.

[0251] 1008. The UDM+HSS sends a second request carrying the eighth information to the AMF based on the seventh information. The second request is used to request the sixth information. Accordingly, the AMF may receive the second request.

[0252] 1009. After determining that UE-1 has enabled LTE capabilities based on the eighth information, the AMF sends the sixth information to the UDM+HSS. Accordingly, the UDM+HSS may receive the sixth information.

[0253] In this embodiment of the present application, after receiving the registration request, the AMF can determine that UE-1 has enabled LTE capabilities. By sending the sixth message to the UDM+HSS after determining that UE-1 has enabled LTE capabilities, it is helpful to prevent AS-1 from making an IMS call to UE-1 before UE-1 enables LTE capabilities, thereby avoiding further call failure.

[0254] In another possible implementation, the first request may not carry the seventh information, and the second request may not carry the eighth information. The protocol may predetermine that the AMF sends the sixth information to the UDM+HSS after determining that UE-1 has enabled LTE capabilities.

[0255] 1010. The UDM+HSS sends the sixth information to AS-1. Accordingly, AS-1 may receive the sixth information.

[0256] 1011. If AS-1 determines based on the sixth information that a call can be made to UE-1 through the IMS domain, AS-1 sends a second call request to UE-1 through the IMS domain. Accordingly, UE-1 may receive the second call request in the IMS domain.

[0257] The detailed description of steps 1007 to 1011 can be found in Figure 9 The description in the corresponding embodiment is not repeated here.

[0258] See Figure 11 , Figure 11 This is a flowchart of a call processing method provided by an embodiment of the present application. The call processing method involves a first terminal device, a first network device, a second network device, a third network device, and a fourth network device. Figure 11 For example, the first terminal device is UE-1, the first network device is P-CSCF-1, the second network device is AS-1, the third network device is UDM+HSS, and the fourth network device is AMF. Figure 11 As shown, the call processing method includes the following parts 1101 to 1111. Among them:

[0259] 1101. AS-1 sends a first call request to UE-1 via the IMS domain. Correspondingly, UE-1 may receive the first call request in the IMS domain.

[0260] 1102. P-CSCF-1 receives second information. The second information is used by P-CSCF-1 to determine that a voice data channel cannot be established for UE-1.

[0261] 1103. P-CSCF-1 sends third information to AS-1. The third information is used by AS-1 to determine whether to call UE-1 through the IMS domain. The third information includes a timer. Accordingly, AS-1 may receive the third information.

[0262] The timer is used for AS-1 to send a first request to the UDM+HSS when the timer expires.

[0263] 1104. P-CSCF-1 sends first information to UE-1, where the first information is used by UE-1 to determine whether to enable LTE capability. Accordingly, UE-1 may receive the first information.

[0264] 1105. UE-1 enables LTE capability.

[0265] 1106. UE-1 sends a registration request to the AMF. The registration request carries UE-1's LTE capability information. Accordingly, the AMF may receive the registration request.

[0266] The detailed description of steps 1107 to 1106 can be found in Figure 9 The description in the corresponding embodiment is not repeated here.

[0267] 1107. When the timer expires, AS-1 sends a first request to the UDM+HSS, where the first request is used to request sixth information, and the sixth information is used to determine whether a call can be made to UE-1 through the IMS domain. Accordingly, the UDM+HSS may receive the first request.

[0268] In the embodiment of the present application, AS-1 sends a first request to UDM+HSS when the timer expires, which helps to prevent AS-1 from making an IMS call to UE-1 earlier than the time when UE-1 activates LTE capability, thereby avoiding the call failing again.

[0269] In another possible implementation, the third information may not carry the timer. The protocol may predefine the timer.

[0270] 1108. The UDM+HSS sends a second request to the AMF, where the second request is for requesting the sixth information. Accordingly, the AMF may receive the second request.

[0271] 1109. The AMF sends the sixth information to the UDM+HSS. Correspondingly, the UDM+HSS may receive the sixth information.

[0272] 1110. The UDM+HSS sends the sixth information to AS-1. Accordingly, AS-1 may receive the sixth information.

[0273] 1111. If AS-1 determines based on the sixth information that a call can be made to UE-1 through the IMS domain, AS-1 sends a second call request to UE-1 through the IMS domain. Accordingly, UE-1 may receive the second call request in the IMS domain.

[0274] The detailed description of steps 1107 to 1111 can be found in Figure 9 The description in the corresponding embodiment is not repeated here.

[0275] See Figure 12 , Figure 12 This is a flowchart of another call processing method provided by an embodiment of the present application. The call processing method involves a first terminal device, a second network device, a third network device, and a fourth network device. Figure 12 For example, the first terminal device is UE-1, the second network device is AS-1, the third network device is UDM+HSS, and the fourth network device is AMF. Figure 12 As shown, the call processing method includes the following parts 1201 to 1204. Among them:

[0276] 1201. The AMF determines that a call cannot be made to UE-1 through the IMS domain.

[0277] In the embodiment of the present application, before the AMF determines that it is impossible to call UE-1 through the IMS domain, it can also be executed Figure 3 That is, after the UDM+HSS requests the AMF to query the availability of UE-1's IMS domain call, the AMF determines that it is not possible to call UE-1 through the IMS domain.

[0278] In one possible implementation, the AMF determines that a call cannot be made to UE-1 through the IMS domain based on UE-1's capability information and / or network capability information. Optionally, UE-1's capability information includes that UE-1 does not support LTE. The network capability information includes one or more combinations of the following: the network does not support VoNR; the network supports EPS fallback; the network does not support 5G and falls back to 2G / 3G to answer calls. Based on this possible implementation, it is possible to accurately determine whether a call can be made to UE-1 through the IMS domain, which helps to avoid call failures.

[0279] For example, if UE-1 does not support LTE, the AMF may determine that a call cannot be made to UE-1 via the IMS domain. For another example, if UE-1 does not support LTE, the network does not support VoNR, and the network supports EPS fallback, the AMF may determine that a call cannot be made to UE-1 via the IMS domain. For another example, if the network does not support VoNR and the network supports EPS fallback, the AMF may determine that a call cannot be made to UE-1 via the IMS domain.

[0280] 1202. The AMF sends first information to UE-1. The first information is used by UE-1 to determine that it has entered the CS domain and is waiting for a call. Accordingly, UE-1 may receive the first information.

[0281] In an embodiment of the present application, after the AMF determines that it is impossible to call UE-1 through the IMS domain, it sends a first message to UE-1.

[0282] In a possible implementation, the AMF may send the first information to UE-1 via a NAS message. If UE-1 is in an idle state, the AMF may first set UE-1 to a connected state via a paging message before sending the NAS message.

[0283] In another possible implementation, the AMF may not send the first information to UE-1. The AMF sends redirection information to the 5G access network device, and the 5G access network device redirects UE-1 to the CS domain.

[0284] 1203. The AMF sends second information to the UDM+HSS, where the second information is used to determine that a call to UE-1 cannot be made through the IMS domain. Accordingly, the UDM+HSS may receive the second information.

[0285] In this embodiment of the present application, after the AMF determines that it cannot call UE-1 via the IMS domain, it sends a second message to the UDM+HSS. After receiving the second message, the UDM+HSS may send the second message to AS-1. After receiving the second message, AS-1 may send a call request to UE-1 via the CS domain. How AS-1 sends the call request to UE-1 via the CS domain is described above and is not repeated here.

[0286] 1204. UE-1 enters the CS domain and waits for a call.

[0287] In the embodiment of the present application, after receiving the first information, UE-1 enters the CS domain and waits for a call.

[0288] It can be seen that through the implementation Figure 12 The described method enables UE-1 to enter the CS domain to wait for a call when a call to UE-1 cannot be made through the IMS domain, and enables the network side to initiate a call to UE-1 through the CS domain, which helps to avoid call failure. Figure 12 The described method is to trigger UE-1 to reselect to the CS network during the called party access domain selection phase. Figure 12 The method is executed early, so the call establishment time can be shortened and the waiting time of the calling party UE can be reduced.

[0289] See Figure 13 , Figure 13 This is a flowchart of another call processing method provided by an embodiment of the present application. The call processing method involves a first terminal device, a second network device, a third network device, a fourth network device, and a fifth network device. Figure 13 For example, the first terminal device is UE-1, the second network device is AS-1, the third network device is UDM+HSS, the fourth network device is AMF, and the fifth network device is MSC. Figure 13 As shown, the call processing method includes the following parts 1301 to 1309. Among them:

[0290] 1301. The AMF determines that a call cannot be made to UE-1 through the IMS domain.

[0291] 1302. The AMF sends first information to UE-1. The first information is used by UE-1 to determine that it has entered the CS domain and is waiting for a call. Accordingly, UE-1 may receive the first information.

[0292] 1303. The AMF sends second information to the UDM+HSS, where the second information is used to determine that a call to UE-1 cannot be made through the IMS domain. Accordingly, the UDM+HSS may receive the second information.

[0293] 1304. The AMF sends the third information to the UDM+HSS. Correspondingly, the UDM+HSS may receive the third information.

[0294] The third information is used by the UDM+HSS to send the second information to the AS-1 after determining that the UE-1 completes the CS domain registration or location update.

[0295] The third information and the second information may be carried in the same message and sent to the UDM+HSS, or the third information and the second information may be carried in different messages and sent to the UDM+HSS.

[0296] 1305. UE-1 reselects to the 2G network or the 3G network.

[0297] In the embodiment of the present application, after receiving the first information, UE-1 reselects to the 2G network or the 3G network.

[0298] 1306. UE-1 sends an attach request or a location update request to the MSC. Correspondingly, the MSC may receive the attach request or the location update request.

[0299] In the embodiment of the present application, after UE-1 reselects to the 2G network or the 3G network, it sends an attach request or a location update request to the MSC.

[0300] 1307. UE-1 waits for a call in the CS domain.

[0301] In the embodiment of the present application, after UE-1 reselects to the 2G network or the 3G network, it waits for a call in the CS domain.

[0302] 1308. The MSC sends a request for updating the location of UE-1 to the UDM+HSS. Correspondingly, the UDM+HSS may receive the request for updating the location of UE-1.

[0303] In the embodiment of the present application, after receiving the attach request or the location update request, the MSC sends a request for updating the location of UE-1 to the UDM+HSS.

[0304] 1309. After determining that UE-1 has completed CS domain registration or location update based on the third information, the UDM+HSS sends the second information to AS-1.

[0305] In this embodiment of the present application, after receiving the request to update UE-1's location, the UDM+HSS may determine that UE-1 has completed CS domain registration or location update. Based on the third information, after determining that UE-1 has completed CS domain registration or location update, the UDM+HSS sends a second message to AS-1. After receiving the second message, AS-1 may initiate a call to UE-1 via the CS domain.

[0306] After determining that UE-1 completes CS domain registration or location update, sending the second information to AS-1 helps prevent AS-1 from making a CS call to UE-1 earlier than UE-1's CS registration completion time, thus avoiding call failure again.

[0307] In another possible implementation, the AMF may not need to send the third information. The protocol may predetermine that the UDM+HSS sends the second information to AS-1 after determining that UE-1 completes CS domain registration or location update.

[0308] In one possible implementation, the UDM+HSS may also send fourth information to AS-1, which is used to route the call to the first terminal device via the CS domain. This accurately routes the call to UE-1. For example, the fourth information may be the CSRN, or other routing information.

[0309] Optionally, the fourth information and the second information may be carried in the same message and sent to AS-1, or the fourth information and the second information may be carried in different messages and sent to AS-1.

[0310] See Figure 14 , Figure 14 This is a flowchart of another call processing method provided by an embodiment of the present application. The call processing method involves a first terminal device, a second network device, a third network device, a fourth network device, and a fifth network device. Figure 14 For example, the first terminal device is UE-1, the second network device is AS-1, the third network device is UDM+HSS, the fourth network device is AMF, and the fifth network device is MSC. Figure 14 As shown, the call processing method includes the following parts 1401 to 1406.

[0311] 1401. The AMF determines that a call cannot be made to UE-1 through the IMS domain.

[0312] 1402. The AMF sends first information to UE-1. The first information is used by UE-1 to determine that it has entered the CS domain and is waiting for a call. Accordingly, UE-1 may receive the first information.

[0313] 1403. The AMF sends second information to the UDM+HSS, where the second information is used to determine that a call to UE-1 cannot be made through the IMS domain. Accordingly, the UDM+HSS may receive the second information.

[0314] The description of steps 1401 to 1403 can be found in Figure 12 The description in the corresponding embodiment is not repeated here.

[0315] 1404. The AMF sends a timer to the UDM+HSS. Correspondingly, the UDM+HSS may receive the timer.

[0316] The timer is used to send the second information to AS-1 when the timer times out.

[0317] The timer and the second information may be carried in the same message and sent to the UDM+HSS, or the timer and the second information may be carried in different messages and sent to the UDM+HSS.

[0318] 1405. UE-1 enters the CS domain and waits for a call.

[0319] 1406. When the timer expires, the UDM+HSS sends the second information to AS-1.

[0320] In the embodiment of the present application, by sending the second information to AS-1 when the timer times out, it is helpful to prevent AS-1 from making a CS call to UE-1 earlier than the CS registration completion time of UE-1, thereby avoiding the call failing again.

[0321] In another possible implementation, the AMF does not need to send a timer to the UDM+HSS. The timer can be pre-defined by the protocol.

[0322] See Figure 15 , Figure 15This is a flowchart of another call processing method provided by an embodiment of the present application. The call processing method involves a first terminal device, a second network device, a third network device, and a fourth network device. Figure 15 For example, the first terminal device is UE-1, the second network device is AS-1, the third network device is UDM+HSS, and the fourth network device is AMF. Figure 15 As shown, the call processing method includes the following parts 1501 to 1505. Among them:

[0323] 1501. The AMF determines that a call cannot be made to UE-1 through the IMS domain.

[0324] In the embodiment of the present application, before the AMF determines that it is impossible to call UE-1 through the IMS domain, it can also be executed Figure 3 That is, after the UDM+HSS requests the AMF to query the availability of UE-1's IMS domain call, the AMF determines that it is not possible to call UE-1 through the IMS domain.

[0325] In one possible implementation, the AMF determines that a call cannot be made to UE-1 through the IMS domain based on UE-1's capability information and / or network capability information. Optionally, UE-1's capability information includes that UE-1 does not support LTE. The network capability information includes one or more of the following: the network does not support Voice over New Radio (VoNR); the network supports Evolved Packet System (EPS) fallback; the network does not support 5G and falls back to 2G / 3G for call reception.

[0326] For example, if UE-1 does not support LTE, the AMF may determine that a call cannot be made to UE-1 through the IMS domain. For another example, if UE-1 does not support LTE, the network does not support Voice over New Radio (VoNR), and the network supports Evolved Packet System (EPS) fallback, the AMF may determine that a call cannot be made to UE-1 through the IMS domain. For another example, if the network does not support Voice over New Radio (VoNR), and the network supports Evolved Packet System (EPS) fallback, the AMF may determine that a call cannot be made to UE-1 through the IMS domain.

[0327] 1502. The AMF sends first information to UE-1. The first information is used by UE-1 to determine whether to enable LTE capability. Accordingly, UE-1 may receive the first information.

[0328] In an embodiment of the present application, after the AMF determines that it is impossible to call UE-1 through the IMS domain, it sends a first message to UE-1.

[0329] In a possible implementation, the AMF may send the first information to UE-1 via a NAS message. If UE-1 is in an idle state, the AMF may first set UE-1 to a connected state via a paging message before sending the NAS message.

[0330] 1503. UE-1 enables LTE capability.

[0331] In the embodiment of the present application, after receiving the first information, UE-1 enables LTE capability.

[0332] 1504. UE-1 sends a registration request to the AMF. The registration request carries UE-1's LTE capability information. Accordingly, the AMF may receive the registration request.

[0333] In this embodiment of the present application, after UE-1 turns on the LTE capability, it sends a registration request to the AMF.

[0334] 1505. After the AMF determines that UE-1 has enabled LTE, it sends second information to the UDM+HSS. The second information is used to confirm that a call to UE-1 can be made through the IMS domain. Accordingly, the UDM+HSS may receive the second information.

[0335] In this embodiment of the present application, after receiving the registration request sent by UE-1, the AMF can determine that UE-1 has enabled LTE capabilities. By sending the second information to the UDM+HSS after determining that UE-1 has enabled LTE capabilities, it is helpful to prevent AS-1 from making an IMS call to UE-1 before UE-1 enables LTE capabilities, thereby avoiding further call failure.

[0336] In the embodiment of the present application, after receiving the second information, the UDM+HSS may send the second information to AS-1. After receiving the second information, AS-1 may send a call request to UE-1 through the IMS domain.

[0337] It can be seen that through the implementation Figure 15 The described method enables UE-1 to enable LTE capability when a call cannot be made to UE-1 through the IMS domain, and enables the network side to initiate a call to UE-1 through the IMS domain, which helps to avoid call failure. Figure 15 The described method is to trigger UE-1 to enable LTE capability during the called party access domain selection phase. Figure 15 The method is executed early, so the call establishment time can be shortened and the waiting time of the calling party UE can be reduced.

[0338] See Figure 16 , Figure 16FIG2 is a flow chart of another call processing method provided by an embodiment of the present application. The call processing method involves a first terminal device and a second network device. Figure 16 Take the first terminal device as UE-1 and the second network device as AS-1 as an example. Figure 16 As shown, the call processing method includes the following parts 1601 to 1605. Among them:

[0339] 1601. AS-1 sends a first call request to UE-1 via the IMS domain. Correspondingly, UE-1 may receive the first call request in the IMS domain.

[0340] The detailed description of step 1601 can be found in the description of step 401 and will not be repeated here.

[0341] 1602. UE-1 determines that call establishment cannot be completed in the IMS domain.

[0342] In the embodiment of the present application, after receiving the first call request, UE-1 determines that the call establishment cannot be completed in the IMS domain.

[0343] In one possible implementation, UE-1 determines that call establishment cannot be completed in the IMS domain as follows: UE-1 determines that call establishment cannot be completed in the IMS domain if a first condition is met; the first condition includes one or more of the following combinations: UE-1's LTE capability is disabled; the 5G signal strength measured by UE-1 is less than a threshold; or, when UE-1 performs 5G registration, the network receives an indication indicating that calls in the IMS domain are not supported. Based on this possible implementation, UE-1 can accurately determine that call establishment cannot be completed in the IMS domain, which helps avoid call failures.

[0344] For example, the first condition includes that the LTE capability of UE-1 is turned off; when UE-1 performs 5G registration, it receives indication information sent by the network to indicate that calls in the IMS domain are not supported.

[0345] For another example, the first condition includes that the 5G signal strength measured by UE-1 is less than a threshold; when UE-1 performs 5G registration, it receives indication information sent by the network to indicate that calls in the IMS domain are not supported.

[0346] For another example, the first condition includes that the LTE capability of UE-1 is turned off; the 5G signal strength measured by UE-1 is less than a threshold; and when UE-1 performs 5G registration, it receives indication information sent by the network indicating that calls in the IMS domain are not supported.

[0347] Optionally, the first condition also includes that the network does not support switching from NG-RAN to UTRAN.

[0348] 1603. UE-1 sends a first message, the first message carrying the identifier of UE-1, and the first message being used to request redirection of the first call request to UE-1. Accordingly, AS-1 may receive the first message.

[0349] In an embodiment of the present application, UE-1 may first send a first message to S-CSCF-1 via P-CSCF-1, which then sends the first message to AS-1. AS-1 processes the first message after receiving it. The first message may be referred to as a redirect message or another name. The first message is used by AS-1 to determine whether to send a second call request to UE-1 via the CS domain. The identifier of UE-1 may be an MSISDN or a uniform resource identifier (SIP URI); a globally routable UAURI (GRUU); or the like.

[0350] The first message may be a 302 message, and the identifier of UE-1 is carried in a contact field of the 302 message.

[0351] 1604. UE-1 enters the CS domain and waits for a call.

[0352] The execution order of step 1603 and step 1604 is not particular.

[0353] 1605. AS-1 sends a second call request to UE-1 through the CS domain.

[0354] In this embodiment of the present application, after receiving the first message, AS-1 sends a second call request to UE-1 via the CS domain. UE-1 sends the first message in order to receive another call request. After receiving the first message, AS-1 may default to sending the second call request to UE-1 via the CS domain. In other words, the first message is used by AS-1 to determine whether to send the second call request to UE-1 via the CS domain. Because AS-1 is within the communication path for UE-1's IMS messages, it can receive and process the first message.

[0355] In one possible implementation, AS-1 sends a second call request to UE-1 via the CS domain as follows: AS-1 sends a first request to the UDM+HSS, where the first request is used to request first information that the call be routed to UE-1 via the CS domain; AS-1 receives the first information sent by the UDM+HSS; and AS-1 sends a second call request to UE-1 via the CS domain based on the first information. Based on this possible implementation, the call can be accurately routed to UE-1. The specific principle of AS-1 sending the second call request to UE-1 via the CS domain can be found in Figure 5 and Figure 6 The description in the corresponding embodiment is not repeated here.

[0356] It can be seen that through the implementation Figure 16 The described method enables UE-1 to enter the CS domain to wait for a call when a call cannot be made to UE-1 through the IMS domain, and enables the network side to initiate a call to UE-1 through the CS domain, which helps to avoid call failure. Figure 16 The described method is to execute an operation of reselecting to a CS network when UE-1 locally determines that a voice call cannot be established after receiving a first call request in the IMS domain. Figure 16 The described method is executed early, thus shortening call establishment time and reducing waiting time for the calling UE. It can also avoid call failures in scenarios where the 5G network does not support VoNR, or where the 5G network supports VoNR but the 5G network signal is poor, thus having a wide range of applications.

[0357] See Figure 17 , Figure 17 This is a flowchart of another call processing method provided by an embodiment of the present application. The call processing method involves a first terminal device, a second network device, a third network device, and a fifth network device. Figure 17 For example, the first terminal device is UE-1, the second network device is AS-1, the third network device is UDM+HSS, and the fifth network device is MSC. Figure 17 As shown, the call processing method includes the following parts 1701 to 1712. Among them:

[0358] 1701. AS-1 sends a first call request to UE-1 via the IMS domain. Correspondingly, UE-1 may receive the first call request in the IMS domain.

[0359] 1702. UE-1 determines that call establishment cannot be completed in the IMS domain.

[0360] 1703. UE-1 sends a first message, the first message carrying the identifier of UE-1, and the first message being used to request redirection of the first call request to UE-1. Accordingly, AS-1 may receive the first message.

[0361] Among them, steps 1701 to 1703 can be found in Figure 16 The description in the corresponding embodiment is not repeated here.

[0362] 1704. UE-1 sends an IMS deregistration request to AS-1. Correspondingly, AS-1 may receive the IMS deregistration request.

[0363] In the embodiment of the present application, UE-1 may first send an IMS deregistration request to S-CSCF-1 through P-CSCF-1, and then S-CSCF-1 sends the IMS deregistration request to AS-1.

[0364] UE-1 sends an IMS deregistration request to notify AS-1 that UE-1 is no longer in the IMS network. Therefore, AS-1, by combining the first message and the IMS deregistration request, can more accurately determine whether to send the second call request to UE-1 via the CS domain. Alternatively, as described above, UE-1 may not send an IMS deregistration request. After receiving the first message, AS-1 defaults to sending the second call request to UE-1 via the CS domain.

[0365] 1705. UE-1 reselects to the 2G network or the 3G network.

[0366] In the embodiment of the present application, after UE-1 receives the first information, UE-1 reselects to the 2G network or the 3G network.

[0367] 1706. UE-1 sends an attach request or a location update request to the MSC. Correspondingly, the MSC may receive the attach request or the location update request.

[0368] In the embodiment of the present application, after UE-1 reselects to the 2G network or 3G network, it sends an attach request or a location update request to the MSC. After UE-1 successfully sends the attach request or the location update request, it indicates that UE-1 has entered the CS domain.

[0369] 1707. UE-1 waits for a call in the CS domain.

[0370] 1708. The MSC sends a request for updating the location of UE-1 to the UDM+HSS. Correspondingly, the UDM+HSS may receive the request for updating the location of UE-1.

[0371] 1709. AS-1 sends a first request carrying second information to the UDM+HSS, where the first request is used to request that the call be routed to UE-1 through the CS domain. Accordingly, the UDM+HSS may receive the first request.

[0372] The second information is used by the UDM+HSS to send the first information to the AS-1 after determining that the UE-1 completes the CS domain registration or location update.

[0373] Optionally, the first information may be a CS domain routing number (CS domain Routing Number, CSRN), or may be other routing information.

[0374] In a possible implementation, the first request may not carry the second information, and the protocol may predetermine that the UDM+HSS sends the first information to the AS-1 after determining that the UE-1 completes the CS domain registration or location update.

[0375] In one possible implementation, the first message carries third information. This third information is used by AS-1 to carry the second information when sending the first request to the UDM+HSS. This allows for greater flexibility in carrying the second information in the first request, eliminating the need to always carry the second information in the first request. Alternatively, the first message may not carry the third information; the protocol predetermines that AS-1 carry the second information when sending the first request to the UDM+HSS.

[0376] 1710. After determining that UE-1 has completed CS domain registration or location update based on the second information, the UDM+HSS sends the first information to AS-1. Accordingly, AS-1 may receive the first information sent by the UDM+HSS.

[0377] UE-1's completion of CS domain registration or location update indicates that UE-1 has successfully entered the CS domain. By sending the first message to AS-1 only after confirming that UE-1 has completed CS domain registration or location update, AS-1 can prevent the CS call to UE-1 from being initiated before UE-1's CS registration is completed, thereby preventing further call failures.

[0378] 1711. AS-1 sends a second call request to UE-1 through the CS domain based on the first information.

[0379] 1712. The MSC sends a call request to UE-1. Correspondingly, UE-1 receives the call request in the CS domain.

[0380] In the embodiment of the present application, after receiving the IAM, the MSC sends a call request to UE-1 based on the IAM. The call request may be called a CS setup message.

[0381] See Figure 18 , Figure 18 This is a flowchart of another call processing method provided by an embodiment of the present application. The call processing method involves a first terminal device, a second network device, and a third network device. Figure 18 For example, the first terminal device is UE-1, the second network device is AS-1, and the third network device is UDM+HSS. Figure 18 As shown, the call processing method includes the following parts 1801 to 1808. Among them:

[0382] 1801. AS-1 sends a first call request to UE-1 via the IMS domain. Correspondingly, UE-1 may receive the first call request in the IMS domain.

[0383] 1802. UE-1 determines that call establishment cannot be completed in the IMS domain.

[0384] 1803. UE-1 sends a first message, the first message carrying the identifier of UE-1, the first message being used to request redirection of the first call request to UE-1, and the first message including a timer. Accordingly, AS-1 may receive the first message.

[0385] 1804. UE-1 sends an IMS deregistration request. Accordingly, AS-1 may receive the IMS deregistration request.

[0386] 1805. UE-1 enters the CS domain and waits for a call.

[0387] Among them, steps 1801 to 1805 can be found in Figure 16 and Figure 17 The description in the corresponding embodiment is not repeated here.

[0388] 1806. When the timer expires, AS-1 sends a first request to the UDM+HSS, where the first request is used to request first information that the call be routed to UE-1 through the CS domain. Accordingly, the UDM+HSS may receive the first request.

[0389] When the timer expires, AS-1 sends a first request to the UDM+HSS. This helps prevent AS-1 from making a CS call to UE-1 before UE-1's CS registration is completed, thus causing the call to fail again.

[0390] In another possible implementation, the first message may not include a timer. The timer may be predefined by a protocol.

[0391] 1807. The UDM+HSS sends the first information to AS-1. Correspondingly, AS-1 may receive the first information sent by the UDM+HSS.

[0392] 1808. AS-1 sends a second call request to UE-1 through the CS domain based on the first information.

[0393] In one possible implementation, AS-1 does not process the first message sent by UE-1. Instead, the first message is sent to UE-2. UE-2 sends another invite message after the timer expires. Based on the fact that UE-1 is deregistered in the IMS, AS-1 selects the CS domain to initiate the request.

[0394] See Figure 19 , Figure 19 FIG2 is a flow chart of another call processing method provided by an embodiment of the present application. The call processing method involves a first terminal device and a second network device. Figure 19 Take the first terminal device as UE-1 and the second network device as AS-1 as an example. Figure 19 As shown, the call processing method includes the following parts 1901 to 1905.

[0395] 1901. AS-1 sends a first call request to UE-1 via the IMS domain. Correspondingly, UE-1 may receive the first call request in the IMS domain.

[0396] The detailed description of step 1901 can be found in the description of step 401 and will not be repeated here.

[0397] 1902. UE-1 determines that call establishment cannot be completed in the IMS domain.

[0398] In the embodiment of the present application, after receiving the first call request, UE-1 determines that the call establishment cannot be completed in the IMS domain.

[0399] In one possible implementation, UE-1 determines that call establishment cannot be completed in the IMS domain as follows: UE-1 determines that call establishment cannot be completed in the IMS domain if a first condition is met; the first condition includes one or more of the following combinations: UE-1's LTE capability is disabled; the 5G signal strength measured by UE-1 is less than a threshold; or, when UE-1 performs 5G registration, the network receives an indication indicating that calls in the IMS domain are not supported. Based on this possible implementation, UE-1 can accurately determine that call establishment cannot be completed in the IMS domain, which helps avoid call failures.

[0400] For example, the first condition includes that the LTE capability of UE-1 is turned off; when UE-1 performs 5G registration, it receives indication information sent by the network to indicate that calls in the IMS domain are not supported.

[0401] For another example, the first condition includes that the 5G signal strength measured by UE-1 is less than a threshold; when UE-1 performs 5G registration, it receives indication information sent by the network to indicate that calls in the IMS domain are not supported.

[0402] For another example, the first condition includes that the LTE capability of UE-1 is turned off; the 5G signal strength measured by UE-1 is less than a threshold; and when UE-1 performs 5G registration, it receives indication information sent by the network indicating that calls in the IMS domain are not supported.

[0403] Optionally, the first condition also includes that the network does not support switching from NG-RAN to UTRAN.

[0404] 1903. UE-1 sends a first message, the first message carrying the identifier of UE-1, and the first message is used to request redirection of the first call request to UE-1. Accordingly, AS-1 may receive the first message.

[0405] In this embodiment of the present application, UE-1 may first send a first message via P-CSCF-1 to S-CSCF-1. S-CSCF-1 then sends the first message to AS-1, which then processes the first message. The first message may be referred to as a redirect message or another name. The first message is used by AS-1 to determine whether to send a second call request to UE-1 via the IMS domain.

[0406] The identifier of UE-1 may be an MSISDN or a uniform resource identifier (SIP URI); a globally routable UAURI (GRUU), or the like.

[0407] The first message may be a 302 message, and the identifier of UE-1 is carried in a contact field of the 302 message.

[0408] 1904. UE-1 enables LTE capability.

[0409] The execution order of step 1903 and step 1904 is not specific.

[0410] 1905. AS-1 sends a second call request to UE-1 via the IMS domain. Correspondingly, UE-1 may receive the second call request.

[0411] In this embodiment of the present application, after receiving the first message, AS-1 sends a second call request to UE-1 via the IMS domain. UE-1 sends the first message in order to receive another call request. After receiving the first message, AS-1 may default to sending the second call request to UE-1 via the IMS domain. In other words, the second call request is used by AS-1 to determine whether to send the second call request to UE-1 via the IMS domain. Because AS-1 is within the communication path for UE-1's IMS message, it can receive and process the first message.

[0412] In one possible implementation, the specific implementation method of AS-1 sending the second call request to the first terminal device through the IMS domain is: AS-1 sends a first request to the third network device, and the first request is used to request the fourth information, and the fourth information is used to determine whether the first terminal device can be called through the IMS domain; AS-1 receives the fourth information sent by the third network device; if AS-1 determines that the first terminal device cannot be called through the IMS domain based on the fourth information, then AS-1 sends the second call request to the first terminal device through the IMS domain. Based on this possible implementation method, AS-1 can query other network devices whether it is currently possible to use the IMS domain to call UE-1, so as to avoid the failure of the call through the IMS domain again. The specific principle of AS-1 sending the second call request to the first terminal device through the IMS domain can be found in Figure 9 The description in the corresponding embodiment is not repeated here.

[0413] It can be seen that through the implementation Figure 19 The described method can enable UE-1 to enable LTE capability when a call to UE-1 cannot be made through the IMS domain, and enable AS-1 to resend the call to UE-1 through the IMS domain, which is helpful to avoid call failure. Figure 19 The described method is to restart the LTE capability when UE-1 locally determines that a voice call cannot be established after receiving a first call request in the IMS domain. Figure 19 The described method is executed early, thus shortening call establishment time and reducing waiting time for the calling UE. It can also avoid call failures in scenarios where the 5G network does not support VoNR, or where the 5G network supports VoNR but the 5G network signal is poor, thus having a wide range of applications.

[0414] See Figure 20 , Figure 20 This is a flowchart of another call processing method provided by an embodiment of the present application. The call processing method involves a first terminal device, a second network device, a third network device, and a fourth network device. Figure 20For example, the first terminal device is UE-1, the second network device is AS-1, the third network device is UDM+HSS, and the fourth network device is AMF. Figure 20 As shown, the call processing method includes the following parts 2001 to 2010. Among them:

[0415] 2001. AS-1 sends a first call request to UE-1 via the IMS domain. Correspondingly, UE-1 may receive the first call request in the IMS domain.

[0416] 2002. UE-1 determines that call establishment cannot be completed in the IMS domain.

[0417] 2003. UE-1 sends a first message, the first message carrying the identifier of UE-1, and the first message is used to request redirection of the first call request to UE-1. Accordingly, AS-1 may receive the first message.

[0418] 2004. UE-1 enables LTE capability.

[0419] The description of steps 2001 to 2004 can be found in Figure 19 The description in the corresponding embodiments will not be repeated here.

[0420] 2005. UE-1 sends a registration request to the AMF. The registration request carries UE-1's LTE capability information. Accordingly, the AMF may receive the registration request.

[0421] In the embodiment of the present application, after UE-1 activates LTE capability, it sends a registration request to the AMF. By executing step 2005, the AMF is able to promptly determine the latest capability information of UE-1.

[0422] 2006. AS-1 sends a first request carrying fifth information to the UDM+HSS. The first request is used to request fourth information. The fourth information is used to determine whether a call can be made to UE-1 through the IMS domain.

[0423] Among them, the fifth information is used by UDM+HSS to carry the sixth information when sending the second request to AMF.

[0424] 2007. The UDM+HSS sends a second request carrying the sixth information to the AMF based on the fifth information. The second request is used to request the fourth information.

[0425] 2008. Based on the sixth information, after determining that UE-1 has enabled the Long Term Evolution (LTE) capability, the AMF sends the fourth information to the UDM+HSS.

[0426] In this embodiment of the present application, after receiving the registration request sent by UE-1, the AMF can determine that UE-1 has enabled LTE capabilities. After determining that UE-1 has enabled LTE capabilities, the AMF sends the fourth message to the UDM+HSS. This helps prevent AS-1 from making an IMS call to UE-1 before UE-1 enables LTE capabilities, thereby avoiding further call failure.

[0427] In another possible implementation, the first request may not carry the fifth information, and the second request may not carry the sixth information. The protocol may predetermine that the AMF sends the fourth information to the UDM+HSS after determining that UE-1 has enabled LTE capabilities.

[0428] In one possible implementation, the first message carries the seventh information, which is used by the second network device to carry the fifth information when sending the first request to the third network device. This allows for greater flexibility in carrying the fifth information in the first request, eliminating the need to always carry the fifth information in the first request. Alternatively, the first message may not carry the seventh information; the protocol predetermines that AS-1 carries the fifth information when sending the first request to the UDM+HSS.

[0429] 2009. UDM+HSS sends the fourth message to AS-1.

[0430] 2010. If AS-1 determines, based on the fourth information, that it is impossible to call UE-1 through the IMS domain, AS-1 sends a second call request to UE-1 through the IMS domain.

[0431] See Figure 21 , Figure 21 This is a flowchart of another call processing method provided by an embodiment of the present application. The call processing method involves a first terminal device, a second network device, a third network device, and a fourth network device. Figure 21 For example, the first terminal device is UE-1, the second network device is AS-1, the third network device is UDM+HSS, and the fourth network device is AMF. Figure 21 As shown, the call processing method includes the following parts 2101 to 2110. Among them:

[0432] 2101. AS-1 sends a first call request to UE-1 via the IMS domain. Correspondingly, UE-1 may receive the first call request in the IMS domain.

[0433] 2102. UE-1 determines that call establishment cannot be completed in the IMS domain.

[0434] 2103. UE-1 sends a first message, the first message carrying the identifier of UE-1, the first message being used to request redirection of the first call request to UE-1, and the first message carrying a timer. Accordingly, AS-1 may receive the first message.

[0435] The timer is used for AS-1 to send a first request to the UDM+HSS when the timer expires.

[0436] 2104. UE-1 enables LTE capability.

[0437] 2105. UE-1 sends a registration request to the AMF. The registration request carries UE-1's LTE capability information. Accordingly, the AMF may receive the registration request.

[0438] The description of steps 2001 to 2004 can be found in Figure 19 and Figure 20 The description in the corresponding embodiments will not be repeated here.

[0439] 2106. When the timer expires, AS-1 sends a first request to the UDM+HSS. The first request is used to request fourth information. The fourth information is used to determine whether a call can be made to UE-1 through the IMS domain.

[0440] In the embodiment of the present application, AS-1 sends a first request to UDM+HSS when the timer expires, which helps to prevent AS-1 from making an IMS call to UE-1 earlier than the time when UE-1 activates LTE capability, thereby avoiding the call failing again.

[0441] 2107. The UDM+HSS sends a second request to the AMF, where the second request is for requesting the fourth information. Accordingly, the AMF may receive the second request.

[0442] 2108. The AMF sends the fourth message to the UDM+HSS. Correspondingly, the UDM+HSS may receive the second request.

[0443] 2109. The UDM+HSS sends the fourth information to AS-1. Accordingly, AS-1 may receive the fourth information.

[0444] 2110. If AS-1 determines based on the fourth information that it is impossible to call UE-1 through the IMS domain, AS-1 sends a second call request to UE-1 through the IMS domain.

[0445] In one possible implementation, AS-1 does not process the first message sent by UE-1, and the first message is sent to UE-2. UE-2 sends an invite message again after the timer expires. AS-1 selects the IMS domain to initiate the request.

[0446] The present application also provides the following embodiments:

[0447] Embodiment 1: A call processing method, wherein the method includes:

[0448] The first terminal device receives first information, wherein the first terminal device resides in a fifth-generation mobile communication technology 5G network, and the long-term evolution LTE capability of the first terminal device is in a closed state. The first information is used by the first terminal device to determine to enter the circuit-switched CS domain to wait for a call, or the first information is used by the first terminal device to turn on the LTE capability; the first terminal device enters the CS domain to wait for a call or the first terminal device turns on the LTE capability.

[0449] Embodiment 2: According to the method of embodiment 1, before the first terminal device receives the first information, the method further includes: the first terminal device receives a first call request in the IP Multimedia System IMS domain.

[0450] Example 3: According to the method of Example 1, the first terminal device receives the first information, including: the first terminal device receives the first information sent by the access and mobility management function AMF.

[0451] Example 4: According to the method of any one of Examples 11 to 3, the first terminal device enters the CS domain to wait for a call, including: the first terminal device reselects to the second-generation mobile communication technology 2G network or the third-generation mobile communication technology 3G network; the first terminal device sends an attachment request or a location update request to the fifth network device; the first terminal device waits for a call in the CS domain.

[0452] Embodiment 5: According to the method of any one of embodiments 1 to 4, after the first terminal device enters the CS domain and waits for a call, the method further includes: the first terminal device receives a call request in the CS domain.

[0453] Example 6. According to the method of any one of Examples 1 to 3, after the first terminal device turns on the LTE capability, the method also includes: the first terminal device sends a registration request to the fourth network device, and the registration request carries the long-term evolution LTE capability information of the first terminal device; the first terminal device receives the second call request in the IP multimedia system IMS domain.

[0454] The relevant operations of the first terminal device in Examples 1 to 6 can be found in the previous Figures 4 to 15 The description of UE-1 in the corresponding embodiment is not repeated here.

[0455] The present application also provides the following embodiments:

[0456] Example 7. A call processing method, wherein the method includes: a first network device receives second information, and the second information is used by the first network device to determine that a voice data channel cannot be established for the first terminal device; the first network device sends third information to the second network device; the first network device sends first information to the first terminal device; wherein the third information is used by the second network device to determine to call the first terminal device through the circuit switching CS domain, and the first information is used by the first terminal device to determine to enter the CS domain to wait for the call; or, the third information is used by the second network device to determine to call the first terminal device through the IP multimedia system IMS domain, and the first information is used by the first terminal device to determine to enable the long-term evolution LTE capability.

[0457] Embodiment 8: According to the method of embodiment 7, the second information is also used by the first network device to determine whether the long term evolution (LTE) capability of the first terminal device is disabled.

[0458] Embodiment 9: According to the method of embodiment 7 or 8, the third information is also used by the second network device to determine whether the LTE capability of the first terminal device is turned off.

[0459] Example 10. According to the method of any one of Examples 7 to 9, the method further includes: the second network device sends a first call request to the first terminal device through the IP Multimedia System IMS domain; the second network device receives the third information sent by the first network device; the second network device sends a second call request to the first terminal device through the CS domain or the IMS domain.

[0460] Example 11: According to the method of Example 10, the second network device sends a second call request to the first terminal device through the CS domain, including: the second network device sends a first request to the third network device, and the first request is used to request that the call be routed to the first terminal device through the CS domain; the second network device receives the fourth information sent by the third network device; the second network device sends the second call request to the first terminal device through the CS domain based on the fourth information.

[0461] Example 12: According to the method of Example 11, the first request carries fifth information; the method also includes: based on the fifth information, the third network device sends fourth information to the second network device after determining that the first terminal device completes CS domain registration or location update.

[0462] Example 13: According to the method of Example 10, the second network device sends a second call request to the first terminal device through the IMS domain, including: the second network device sends a first request to the third network device, the first request is used to request sixth information, and the sixth information is used to determine whether a call can be made to the first terminal device through the IMS domain; the second network device receives the sixth information sent by the third network device; if the second network device determines that the call can be made to the first terminal device through the IMS domain based on the sixth information, the second network device sends the second call request to the first terminal device through the IMS domain.

[0463] Example 14: According to the method of Example 13, the first request carries seventh information, and the method also includes: the third network device sends a second request carrying eighth information to the fourth network device based on the seventh information, and the second request is used to request sixth information; the fourth network device sends sixth information to the third network device based on the eighth information after determining that the first terminal device has enabled Long Term Evolution (LTE) capability; the third network device sends the sixth information to the second network device.

[0464] Example 15: According to the method of Example 11 or 13, the third information includes a timer; the second network device sends a first request to the third network device, including: the second network device sends the first request to the third network device when the timer expires.

[0465] The related operations of the network devices in Examples 7 to 15 can be found in Figures 4 to 11 The description of network devices in [1] is not repeated here.

[0466] The present application also provides the following embodiments:

[0467] Example 16: A call processing method, the method comprising: a fourth network device determines that a call cannot be made to a first terminal device through an IP Multimedia System (IMS) domain; the fourth network device sends a first message to the first terminal device, the first message being used by the first terminal device to determine to enter a CS domain to wait for a call; the fourth network device sends a second message to a third network device, the second message being used to determine that a call cannot be made to the first terminal device through the IMS domain.

[0468] Example 17. According to the method of Example 16, the fourth network device determines that it is impossible to call the first terminal device through the IP Multimedia System IMS domain, including: the fourth network device determines that it is impossible to call the first terminal device through the IMS domain based on the capability information and / or network capability information of the first terminal device; the capability information of the first terminal device includes that the first terminal device does not support Long Term Evolution LTE; the network capability information includes one or more combinations of the following: the network does not support Voice over New Radio (VoNR); the network supports Evolved Packet System (EPS) fallback; the network does not support the fifth generation mobile communication technology (5G) and falls back to 2G / 3G to answer calls.

[0469] Example 18: According to the method of Example 16 or 17, the method also includes: the fourth network device sends third information to the third network device; based on the third information, the third network device sends second information to the second network device after determining that the first terminal device completes CS domain registration or location update.

[0470] Embodiment 19: According to the method of embodiment 16 or 17, the method further includes: the fourth network device sends a timer to the third network device; when the timer expires, the third network device sends the second information to the second network device.

[0471] Embodiment 20: According to the method of embodiment 18 or 19, the method further includes: the third network device sends fourth information to the second network device, and the fourth information is used to route the call to the first terminal device through the circuit switching CS domain.

[0472] Example 21: According to the method of any one of Examples 16 to 20, the fourth network device is an access and mobility management function AMF.

[0473] The related operations of the network devices in Examples 16 to 21 can be found in Figures 12 to 14 The description of network devices in [1] is not repeated here.

[0474] The present application also provides the following embodiments:

[0475] Example 22. A call processing method, wherein the method includes: the fourth network device determines that a call cannot be made to the first terminal device through the IP Multimedia System IMS domain; the fourth network device sends first information to the first terminal device, and the first information is used by the first terminal device to determine whether to enable Long Term Evolution (LTE) capability; after the fourth network device determines that the first terminal device has enabled LTE capability, the fourth network device sends second information to the third network device, and the second information is used to determine that a call can be made through the IMS domain.

[0476] Example 23. According to the method of Example 22, the fourth network device determines that it is impossible to call the first terminal device through the IP Multimedia System IMS domain, including: the fourth network device determines that it is impossible to call the first terminal device through the IP Multimedia System IMS domain based on the capability information and / or network capability information of the first terminal device; the capability information of the first terminal device includes that the first terminal device does not support Long Term Evolution LTE; the network capability information includes one or more combinations of the following: the network does not support new air interface voice VoNR, supports evolved packet system EPS fallback, and the network does not support the fifth generation mobile communication technology 5G and falls back to the second generation mobile communication technology 2G / third generation mobile communication technology 3G to answer calls.

[0477] Example 24: According to the method of Example 22 or 23, the fourth network device is an access and mobility management function AMF.

[0478] The related operations of the network devices in Examples 22 to 24 can be found in Figure 15 The description of network devices in [1] is not repeated here.

[0479] The present application also provides the following embodiments:

[0480] Example 25. A call processing method, wherein the method includes: a first terminal device receives a first call request in an IP multimedia system IMS domain; the first terminal device determines that the call establishment cannot be completed in the IMS domain; the first terminal device sends a first message, which carries an identifier of the first terminal device, and the first message is used to request that the first call request be redirected to the first terminal device; the first terminal device enters the CS domain to wait for a call or the first terminal device activates the long-term evolution LTE capability.

[0481] Embodiment 26: According to the method of embodiment 25, before the first terminal device enters the CS domain to wait for a call, the method further includes: the first terminal device sends an IMS deregistration request.

[0482] Example 27. According to the method of Example 25 or 26, the first terminal device determines that the call establishment cannot be completed in the IMS domain, including: if the first condition is met, the first terminal device determines that the call establishment cannot be completed in the IMS domain; the first condition includes one or more combinations of the following: the long-term evolution LTE capability of the first terminal device is turned off; the 5G signal strength measured by the first terminal device is less than a threshold; when the first terminal device performs fifth-generation mobile communication technology 5G registration, it receives indication information sent by the network to indicate that calls in the IMS domain are not supported.

[0483] Example 28: According to the method of Example 27, the first condition also includes that the network does not support switching from NG-RAN to UTRAN.

[0484] Example 29. According to the method of any one of Examples 25 to 28, the first message carries third information, and the third information is used to carry the second information when the second network device sends a first request to the third network device; the first request is used to request the first information to route the call to the first terminal device through the CS domain, and the second information is used by the third network device to send the first information to the second network device after determining that the first terminal device has completed CS domain registration or location update.

[0485] Example 30. According to the method of any one of Examples 25 to 28, the first message carries seventh information, and the seventh information is used by the second network device to carry fifth information when sending a first request to the third network device; the first request is used to request fourth information, and the fourth information is used to determine whether a call can be made to the first terminal device through the IMS domain; the fifth information is used by the third network device to carry sixth information when sending a second request to the fourth network device, and the second request is used to request fourth information, and the sixth information is used by the fourth network device to send the fourth information to the third network device after determining that the first terminal device has enabled the Long Term Evolution (LTE) capability.

[0486] Example 31: According to the method of any one of Examples 25 to 28, the first message further carries a timer, and the timer is used by the second network device to initiate a call to the first terminal device through the CS domain or the IMS domain when the timer expires.

[0487] Example 32: According to the method of any one of Examples 25 to 31, the first terminal device enters the CS domain to wait for a call, including: the first terminal device reselects to the second-generation mobile communication technology 2G network or the third-generation mobile communication technology 3G network; the first terminal device sends an attachment request or a location update request to the mobile switching center MSC; the first terminal device waits for a call in the CS domain.

[0488] Embodiment 33: According to the method of any one of Embodiments 25 to 32, after the first terminal device enters the CS domain to wait for a call, the method further includes: the first terminal device receives a second call request in the CS domain.

[0489] Example 34. According to the method of any one of Examples 25 to 31, after the first terminal device turns on the LTE capability, the method also includes: the first terminal device sends a registration request to the fourth network device, and the registration request carries the long-term evolution LTE capability; the first terminal device receives the second call request in the IP multimedia system IMS domain.

[0490] The related operations of the first terminal device in Examples 25 to 34 can be found in Figures 16 to 21 The relevant description of the first terminal device in will not be repeated here.

[0491] The present application also provides the following embodiments:

[0492] Example 35. A call processing method, the method comprising: a second network device sends a first call request to a first terminal device through an IP multimedia system IMS domain; the second network device receives a first message sent by the first terminal device, the first message carries an identifier of the first terminal device, and the first message is used to request that the first call request be redirected to the first terminal device; the second network device sends a second call request to the first terminal device through a CS domain or an IMS domain.

[0493] Example 36: According to the method of Example 35, before the second network device sends a second call request to the first terminal device through the CS domain, the method further includes: the second network device receives an IMS deregistration request sent by the first terminal device.

[0494] Example 37. According to the method of Example 35 or 36, the second network device sends a second call request to the first terminal device through the CS domain, including: the second network device sends a first request to the third network device, and the first request is used to request that the call be routed to the first terminal device through the CS domain; the second network device receives the first information sent by the third network device; the second network device sends the second call request to the first terminal device through the CS domain based on the first information.

[0495] Example 38: According to the method of Example 37, the first request carries the second information, and the method also includes: based on the second information, the third network device sends the first information to the second network device after determining that the first terminal device completes CS domain registration or location update.

[0496] Example 39: According to the method of Example 38, the first message carries third information, and the third information is used to carry the second information when the second network device sends the first request to the third network device.

[0497] Example 40: According to the method of Example 35, the second network device sends a second call request to the first terminal device through the IMS domain, including: the second network device sends a first request to the third network device, the first request is used to request fourth information, and the fourth information is used to determine whether a call can be made to the first terminal device through the IMS domain; the second network device receives the fourth information sent by the third network device; if the second network device determines that the call cannot be made to the first terminal device through the IMS domain based on the fourth information, the second network device sends the second call request to the first terminal device through the IMS domain.

[0498] Example 41. According to the method of Example 40, the first request carries fifth information, and the method also includes: the third network device sends a second request carrying sixth information to the fourth network device based on the fifth information, and the second request is used to request the fourth information; the fourth network device sends the fourth information to the third network device after determining that the first terminal device has enabled the Long Term Evolution (LTE) capability based on the sixth information; the third network device sends the fourth information to the second network device.

[0499] Example 42: According to the method of Example 41, the first message carries seventh information, and the seventh information is used to carry the fifth information when the second network device sends the first request to the third network device.

[0500] Example 43: The method according to Example 37 or 40 is characterized in that the first message includes a timer; the second network device sends a first request to the third network device, including: the second network device sends the first request to the third network device when the timer expires.

[0501] Among them, the related operations of the network devices in Examples 35 to 43 can be found in Figures 16 to 21 The description of network devices in [1] is not repeated here.

[0502] See Figure 22 , Figure 22 A schematic structural diagram of a communication device according to an embodiment of the present application is shown. Figure 22 The communication device shown can be used to perform the above Figures 4 to 15 The device may be the first terminal device, or a device within the first terminal device, or a device capable of being used in conjunction with the first terminal device. The communication device may also be a chip system. Figure 22 The communication device shown may include a communication unit 2201 and a processing unit 2202. The processing unit 2202 is configured to perform data processing. The communication unit 2201 integrates a receiving unit and a transmitting unit. The communication unit 2201 may also be referred to as a transceiver unit. Alternatively, the communication unit 2201 may be split into a receiving unit and a transmitting unit. The processing unit 2202 and the communication unit 2201 described below are similar and will not be further described.

[0503] in:

[0504] The communication unit 2201 is used to receive first information, wherein the communication device resides in a fifth-generation mobile communication technology 5G network, and the long-term evolution LTE capability of the communication device is in a disabled state. The first information is used by the communication device to determine whether to enter a circuit-switched CS domain to wait for a call, or the first information is used by the communication device to enable LTE capability; the processing unit 2202 is used to enter the CS domain to wait for a call or enable LTE capability.

[0505] In a possible implementation, the communication unit 2201 is further configured to receive a first call request in an IP Multimedia System (IMS) domain before receiving the first information.

[0506] In a possible implementation manner, the communication unit 2201 receives the first information in the following manner: the communication unit 2201 receives the first information sent by the access and mobility management function AMF.

[0507] In one possible implementation, the processing unit 2202 enters the CS domain to wait for a call by: reselecting to the second generation mobile communication technology 2G network or the third generation mobile communication technology 3G network; sending an attachment request or a location update request to the fifth network device; and waiting for a call in the CS domain.

[0508] In a possible implementation, the communication unit 2201 is further configured to receive a call request in the CS domain after the processing unit 2202 enters the CS domain to wait for a call.

[0509] In one possible implementation, the communication unit 2201 is further used to send a registration request to the fourth network device after the processing unit 2202 turns on the LTE capability, and the registration request carries the long-term evolution LTE capability information of the communication device; the communication unit 2201 is also used to receive a second call request in the IP multimedia system IMS domain.

[0510] See Figure 22 , Figure 22 A schematic structural diagram of a communication device according to an embodiment of the present application is shown. Figure 22 The communication device shown can be used to perform the above Figure 15 The method embodiment described herein may include some or all of the functions of the fourth network device. The device may be the fourth network device, a device within the fourth network device, or a device capable of being used in conjunction with the fourth network device. The communication device may also be a chip system. Figure 22 The communication device shown may include a communication unit 2201 and a processing unit 2202.

[0511] The processing unit 2202 is used to determine that a call cannot be made to the first terminal device through the IP Multimedia System IMS domain; the communication unit 2201 is used to send first information to the first terminal device, and the first information is used by the first terminal device to determine whether to enable the Long Term Evolution (LTE) capability; the communication unit 2201 is also used to send second information to the third network device after determining that the first terminal device has enabled the LTE capability, and the second information is used to determine that a call can be made through the IMS domain.

[0512] In one possible implementation, the processing unit 2202 determines that a call cannot be made to the first terminal device through the IP Multimedia System IMS domain in the following specific manner: determining that a call cannot be made to the first terminal device through the IP Multimedia System IMS domain based on the capability information and / or network capability information of the first terminal device; the capability information of the first terminal device includes that the first terminal device does not support Long Term Evolution LTE; the network capability information includes one or more combinations of the following: the network does not support Voice over New Radio (VoNR), supports Evolved Packet System (EPS) fallback, and the network does not support the fifth generation mobile communication technology 5G and falls back to the second generation mobile communication technology 2G / third generation mobile communication technology 3G to answer calls.

[0513] In a possible implementation, the communication device is an access and mobility management function AMF.

[0514] See Figure 22 , Figure 22 A schematic structural diagram of a communication device according to an embodiment of the present application is shown. Figure 22 The communication device shown can be used to perform the above Figures 16 to 21 The device may be the first terminal device, or a device within the first terminal device, or a device capable of being used in conjunction with the first terminal device. The communication device may also be a chip system. Figure 22 The communication device shown may include a communication unit 2201 and a processing unit 2202.

[0515] Communication unit 2201 is used to receive a first call request in the IP Multimedia System IMS domain; processing unit 2202 is used to determine that the call establishment cannot be completed in the IMS domain; communication unit 2201 is also used to send a first message, which carries the identifier of the first terminal device, and the first message is used to request that the first call request be redirected to the first terminal device; processing unit 2202 is also used to enter the CS domain to wait for the call or for the first terminal device to enable long-term evolution LTE capability.

[0516] In a possible implementation, the communication unit 2201 is further configured to send an IMS deregistration request before the processing unit 2202 enters the CS domain to wait for a call.

[0517] In one possible implementation, the processing unit 2202 determines that the call establishment cannot be completed in the IMS domain in the following specific manner: if the first condition is met, it is determined that the call establishment cannot be completed in the IMS domain; the first condition includes one or more combinations of the following: the long-term evolution LTE capability of the first terminal device is turned off; the 5G signal strength measured by the first terminal device is less than a threshold; when the first terminal device performs fifth-generation mobile communication technology 5G registration, it receives indication information sent by the network to indicate that calls in the IMS domain are not supported.

[0518] In a possible implementation, the first condition also includes that the network does not support switching from NG-RAN to UTRAN.

[0519] In one possible implementation, the first message carries third information, and the third information is used to carry the second information when the second network device sends a first request to the third network device; the first request is used to request the first information to route the call to the first terminal device through the CS domain, and the second information is used by the third network device to send the first information to the second network device after determining that the first terminal device has completed CS domain registration or location update.

[0520] In one possible implementation, the first message carries seventh information, and the seventh information is used by the second network device to carry fifth information when sending a first request to the third network device; the first request is used to request fourth information, and the fourth information is used to determine whether a call can be made to the first terminal device through the IMS domain; the fifth information is used by the third network device to carry sixth information when sending a second request to the fourth network device, and the second request is used to request fourth information, and the sixth information is used by the fourth network device to send the fourth information to the third network device after determining that the first terminal device has enabled the long-term evolution LTE capability.

[0521] In a possible implementation, the first message further carries a timer, and the timer is used for the second network device to initiate a call to the first terminal device through the CS domain or the IMS domain when the timer expires.

[0522] In a possible implementation, the processing unit 2202 enters the CS domain to wait for a call by: reselecting to the second generation mobile communication technology 2G network or the third generation mobile communication technology 3G network; sending an attach request or a location update request to the mobile switching center MSC; and waiting for a call in the CS domain.

[0523] In a possible implementation, the communication unit 2201 is further configured to receive a second call request in the CS domain after the processing unit 2202 enters the CS domain to wait for a call.

[0524] In one possible implementation, the communication unit 2201 is further configured to, after the processing unit 2202 enables the LTE capability, send a registration request to the fourth network device, the registration request carrying the Long Term Evolution (LTE) capability; and receive a second call request in the IP Multimedia System (IMS) domain.

[0525] Figure 23 A schematic diagram of the structure of a communication device is provided. The communication device 2300 can be the first terminal device in the above method embodiment, or it can be a network device in the above method embodiment. The network device can be any one of the first network device to the fifth network device. It can also be a chip, chip system, or processor that supports the first terminal device to implement the above method, or it can be a chip, chip system, or processor that supports the network device to implement the above method. This communication device can be used to implement the method described in the above method embodiment. For details, please refer to the description of the above method embodiment.

[0526] The communication device 2300 may include one or more processors 2301. The processor 2301 may be a general-purpose processor or a dedicated processor. For example, it may be a baseband processor or a central processing unit (CPU). The baseband processor may be used to process communication protocols and communication data, while the CPU may be used to control the communication device (e.g., a base station, a baseband chip, a terminal, a terminal chip, a DU or a CU), execute software programs, and process software program data.

[0527] Optionally, the communication device 2300 may include one or more memories 2302, on which instructions 2304 may be stored. The instructions may be executed on the processor 2301, causing the communication device 2300 to perform the method described in the above method embodiment. Optionally, the memory 2302 may also store data. The processor 2301 and memory 2302 may be provided separately or integrated together.

[0528] Optionally, the communication device 2300 may further include a transceiver 2305 and an antenna 2306. The transceiver 2305 may be referred to as a transceiver unit, a transceiver, or a transceiver circuit, etc., and is configured to implement transceiver functions. The transceiver 2305 may include a receiver and a transmitter. The receiver may be referred to as a receiver or a receiving circuit, etc., and is configured to implement a receiving function; the transmitter may be referred to as a transmitter or a transmitting circuit, etc., and is configured to implement a transmitting function.

[0529] The communication device 2300 is a terminal device: the processor 2301 is used to perform the data processing operation of the first terminal device in the above method embodiment. The transceiver 2305 is used to perform the data receiving and sending operation of the first terminal device in the above method embodiment.

[0530] The communication device 2300 is a network device: the processor 2301 is used to perform the data processing operation of the network device in the above method embodiment. The transceiver 2305 is used to perform the data receiving and sending operation of the network device in the above method embodiment.

[0531] In another possible design, processor 2301 may include a transceiver for implementing receiving and transmitting functions. For example, the transceiver may be a transceiver circuit, an interface, or an interface circuit. The transceiver circuit, interface, or interface circuit for implementing the receiving and transmitting functions may be separate or integrated. The transceiver circuit, interface, or interface circuit may be used for reading and writing code / data, or the transceiver circuit, interface, or interface circuit may be used for transmitting or delivering signals.

[0532] In another possible design, processor 2301 may optionally store instructions 2303. Instructions 2303 run on processor 2301 to enable communication device 2300 to perform the method described in the above method embodiment. Instructions 2303 may be fixed in processor 2301. In this case, processor 2301 may be implemented by hardware.

[0533] In another possible design, the communication device 2300 may include a circuit that can implement the functions of sending, receiving, or communicating in the aforementioned method embodiments. The processor and transceiver described in the embodiments of the present application can be implemented in an integrated circuit (IC), an analog IC, a radio frequency integrated circuit RFIC, a mixed signal IC, an application specific integrated circuit (ASIC), a printed circuit board (PCB), an electronic device, etc. The processor and transceiver can also be manufactured using various IC process technologies, such as complementary metal oxide semiconductor (CMOS), N-type metal oxide semiconductor (nMetal-oxide-semiconductor, NMOS), P-type metal oxide semiconductor (positive channelmetal oxide semiconductor, PMOS), bipolar junction transistor (Bipolar Junction Transistor, BJT), bipolar CMOS (BiCMOS), silicon germanium (SiGe), gallium arsenide (GaAs), etc.

[0534] The communication device described in the above embodiments may be a terminal device or a network device, but the scope of the communication device described in the embodiments of the present application is not limited thereto, and the structure of the communication device may not be limited thereto. Figure 23 The communication device may be an independent device or may be part of a larger device. For example, the communication device may be:

[0535] (1) An independent integrated circuit (IC), or chip, or chip system or subsystem;

[0536] (2) A set of one or more ICs, optionally including a storage component for storing data and instructions;

[0537] (3) ASIC, such as modem (MSM);

[0538] (4) Modules that can be embedded in other devices;

[0539] (5) Receivers, terminals, smart terminals, cellular phones, wireless devices, handheld devices, mobile units, vehicle-mounted devices, network devices, cloud devices, artificial intelligence devices, etc.;

[0540] (6)Others, etc.

[0541] For the case where the communication device may be a chip or a chip system, see Figure 24 Schematic diagram of the chip structure shown. Figure 24 The chip 2400 shown includes a processor 2401 and an interface 2402. Optionally, it may also include a memory 2403. The number of the processors 2401 may be one or more, and the number of the interfaces 2402 may be multiple.

[0542] In one design, for a case where the chip is used to implement the functions of the first terminal device in the embodiments of the present application:

[0543] The interface 2402 is used to receive or output signals;

[0544] The processor 2401 is configured to execute the data processing operation of the first terminal device in the above method embodiment.

[0545] In another design, for the case where the chip is used to implement the functions of the network device in the embodiments of the present application:

[0546] The interface 2402 is used to receive or output signals;

[0547] The processor 2401 is configured to execute the data processing operation of the network device in the above method embodiment.

[0548] It is understandable that some optional features in the embodiments of the present application may, in certain scenarios, be implemented independently of other features, such as the solution on which they are currently based, to solve corresponding technical problems and achieve corresponding effects. They may also be combined with other features in certain scenarios as needed. Accordingly, the communication device provided in the embodiments of the present application may also implement these features or functions accordingly, which will not be described in detail here.

[0549] It should be understood that the processor in the embodiment of the present application can be an integrated circuit chip with signal processing capabilities. In the implementation process, each step of the above method embodiment can be completed by an integrated logic circuit of hardware in the processor or instructions in the form of software. The above processor can be a general-purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic device, discrete hardware component.

[0550] It is understood that the memory in the embodiments of the present application may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memories. Among them, the non-volatile memory may be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory may be a random access memory (RAM), which is used as an external cache. By way of example and not limitation, many forms of RAM are available, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), and direct RAM bus RAM (DR RAM). It should be noted that the memory of the systems and methods described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0551] The present application also provides a communication system, including a first terminal device and a network device, wherein the first terminal device is used to execute the method described in any one of Examples 1 to 6; the network device is used to execute the method described in any one of Examples 7 to 15, or the network device is used to execute the method described in any one of Examples 16 to 21, or the network device is used to execute the method described in any one of Examples 22 to 24.

[0552] The present application also provides a communication system including a first terminal device and a network device, wherein the first terminal device is used to execute the method described in any one of Examples 25 to 34; and the network device is used to execute the method described in any one of Examples 35 to 43.

[0553] The present application also provides a computer-readable medium, in which computer-executable instructions are stored. When the computer-readable instructions are called by the computer, the computer-executable instructions are used to cause the computer to execute the method described in any one of the above embodiments 1-6, or, when the computer-executable instructions are called by the computer, the computer-executable instructions are used to cause the computer to execute the method described in any one of the above embodiments 22-24, or, when the computer-executable instructions are called by the computer, the computer-executable instructions are used to cause the computer to execute the method described in any one of the above embodiments 25-34.

[0554] The present application also provides a computer program product for storing computer software instructions, which, when executed by a communication device, implements the method described in any one of the above embodiments 1-6, or the method described in any one of the above embodiments 22-24, or the method described in any one of the above embodiments 25-34.

[0555] In the above embodiments, all or part of the embodiments may be implemented by software, hardware, firmware, or any combination thereof. When implemented using software, all or part of the embodiments may be implemented in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of the present application are generated. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions may be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via a wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) method. The computer-readable storage medium may be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more available media integrated therein. The available medium may be a magnetic medium (eg, a floppy disk, a hard disk, a magnetic tape), an optical medium (eg, a high-density digital video disc (DVD)), or a semiconductor medium (eg, a solid state disk (SSD)).

[0556] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A call processing method, characterized in that: The method comprises: A first terminal device receives first information, wherein the first terminal device resides in a fifth-generation mobile communication technology 5G network, and the long-term evolution LTE capability of the first terminal device is in a disabled state. The first information is used by the first terminal device to determine to enter a circuit-switched CS domain to wait for a call, or the first information is used by the first terminal device to enable the LTE capability; The first terminal device enters the CS domain to wait for a call or the first terminal device turns on the LTE capability; The first terminal device receives a call request; wherein, the call request is a call request in the CS domain, and the call request is initiated after determining that the first terminal device completes CS domain registration or location update; or, the call request is a call request in the IP Multimedia System IMS domain, and the call request is initiated after determining that the first terminal device has enabled LTE capability.

2. The method according to claim 1, characterized in that Before the first terminal device receives the first information, the method further includes: The first terminal device receives a first call request in an IP Multimedia System (IMS) domain.

3. The method according to claim 1, characterized in that The first terminal device receives the first information, including: The first terminal device receives the first information sent by the access and mobility management function AMF.

4. The method according to any one of claims 1 to 3, characterized in that The first terminal device enters the CS domain and waits for a call, including: The first terminal device reselects to a second generation mobile communication technology 2G network or a third generation mobile communication technology 3G network; The first terminal device sends an attachment request or a location update request to the fifth network device; The first terminal device waits for a call in the CS domain.

5. The method according to any one of claims 1 to 3, characterized in that After the first terminal device enters the CS domain and waits for a call, the first terminal device receives a call request, including: The first terminal device receives a call request in the CS domain.

6. The method according to any one of claims 1 to 3, characterized in that After the first terminal device enables the LTE capability, the first terminal device receives a call request, including: The first terminal device sends a registration request to the fourth network device, where the registration request carries the long term evolution (LTE) capability information of the first terminal device; The first terminal device receives a second call request in the IP Multimedia System IMS domain.

7. A call processing method, characterized in that: The method comprises: The first network device receives second information, where the second information is used by the first network device to determine that a voice data channel cannot be established for the first terminal device; the first network device determines that a long-term evolution (LTE) capability of the first terminal device is disabled; The first network device sends third information to the second network device; The first network device sends first information to the first terminal device; The third information is used by the second network device to determine to call the first terminal device through the circuit switching CS domain, and the first information is used by the first terminal device to determine to enter the CS domain to wait for the call, and the call is initiated after determining that the first terminal device completes the CS domain registration or location update; or, the third information is used by the second network device to determine to call the first terminal device through the IP multimedia system IMS domain, and the first information is used by the first terminal device to determine to enable the long-term evolution LTE capability, and the call is initiated after determining that the first terminal device enables the LTE capability.

8. The method according to claim 7, characterized in that The second information is also used by the first network device to determine that the long term evolution (LTE) capability of the first terminal device is disabled.

9. The method according to claim 7 or 8, characterized in that The third information is also used by the second network device to determine that the LTE capability of the first terminal device is turned off.

10. The method according to claim 7, characterized in that The method further comprises: The second network device sends a first call request to the first terminal device through the IP Multimedia System IMS domain; The second network device receives the third information sent by the first network device; The second network device sends a second call request to the first terminal device through the CS domain or the IMS domain.

11. The method according to claim 10, characterized in that The second network device sending a second call request to the first terminal device through the CS domain includes: The second network device sends a first request to the third network device, where the first request is used to request that the call be routed to the first terminal device through the CS domain; The second network device receives the fourth information sent by the third network device; The second network device sends a second call request to the first terminal device through the CS domain based on the fourth information.

12. The method according to claim 11, characterized in that The first request carries fifth information; and the method further includes: Based on the fifth information, the third network device sends the fourth information to the second network device after determining that the first terminal device completes CS domain registration or location update.

13. The method according to claim 10, characterized in that The second network device sending a second call request to the first terminal device through the IMS domain includes: The second network device sends a first request to the third network device, where the first request is used to request sixth information, and the sixth information is used to determine whether a call can be made to the first terminal device through the IMS domain; The second network device receives the sixth information sent by the third network device; If the second network device determines, based on the sixth information, that a call can be made to the first terminal device through the IMS domain, the second network device sends a second call request to the first terminal device through the IMS domain.

14. The method according to claim 13, characterized in that The first request carries seventh information, and the method further includes: The third network device sends a second request carrying eighth information to the fourth network device based on the seventh information, where the second request is used to request the sixth information; The fourth network device sends the sixth information to the third network device after determining, based on the eighth information, that the first terminal device has enabled the Long Term Evolution (LTE) capability; The third network device sends the sixth information to the second network device.

15. The method according to claim 11 or 13, characterized in that The third information includes a timer; The second network device sending a first request to the third network device includes: When the timer times out, the second network device sends a first request to the third network device.

16. A call processing method, characterized in that: The method comprises: The fourth network device determines, based on the capability information and / or network capability information of the first terminal device, that a call cannot be made to the first terminal device through the IP Multimedia System IMS domain; the capability information of the first terminal device includes that the first terminal device does not support Long Term Evolution (LTE); the network capability information includes one or more combinations of the following: the network does not support Voice over New Radio (VoNR); the network supports Evolved Packet System (EPS) fallback; the network does not support the fifth generation mobile communication technology (5G) and falls back to 2G / 3G to answer the call; The fourth network device sends first information to the first terminal device, where the first information is used by the first terminal device to determine that it enters the CS domain and waits for a call; The fourth network device sends second information to the third network device to send the second information to the second network device through the third network device, where the second information is sent by the third network device to the second network device after determining that the first terminal device completes CS domain registration or location update or the timer expires, and the second information is used to determine that a call cannot be made to the first terminal device through the IMS domain.

17. The method according to claim 16, characterized in that The method further comprises: The fourth network device sends third information to the third network device; Based on the third information, the third network device sends the second information to the second network device after determining that the first terminal device completes CS domain registration or location update.

18. The method according to claim 16, characterized in that The method further comprises: The fourth network device sends a timer to the third network device; When the timer times out, the third network device sends the second information to the second network device.

19. The method according to claim 17 or 18, characterized in that The method further comprises: The third network device sends fourth information to the second network device, where the fourth information is used to route the call to the first terminal device through a circuit switched CS domain.

20. The method according to claim 16, wherein The fourth network device is an access and mobility management function AMF.

21. A call processing method, characterized in that: The method comprises: The fourth network device determines, based on the capability information and / or network capability information of the first terminal device, that a call cannot be made to the first terminal device through the IP Multimedia System IMS domain; the capability information of the first terminal device includes that the first terminal device does not support Long Term Evolution LTE; the network capability information includes one or more combinations of the following: the network does not support Voice over New Radio (VoNR), supports Evolved Packet System (EPS) fallback, and the network does not support the fifth generation mobile communication technology (5G) and falls back to the second generation mobile communication technology (2G) / third generation mobile communication technology (3G) to answer the call; The fourth network device sends first information to the first terminal device, where the first information is used by the first terminal device to determine whether to enable Long Term Evolution (LTE) capability; After determining that the first terminal device has enabled the LTE capability, the fourth network device sends second information to the third network device, where the second information is used to determine that a call can be made through the IMS domain.

22. The method according to claim 21, characterized in that The fourth network device is an access and mobility management function AMF.

23. A call processing method, characterized in that: The method comprises: The first terminal device receives a first call request in the IP Multimedia System IMS domain; If the first condition is met, the first terminal device determines that the call establishment cannot be completed in the IMS domain; the first terminal device resides in a fifth-generation mobile communication technology 5G network, and the first condition includes one or more combinations of the following: the long-term evolution LTE capability of the first terminal device is turned off; the 5G signal strength measured by the first terminal device is less than a threshold; when the first terminal device performs fifth-generation mobile communication technology 5G registration, it receives indication information sent by the network to indicate that calls in the IMS domain are not supported; The first terminal device sends a first message, where the first message carries an identifier of the first terminal device, and the first message is used to request that the first call request be redirected to the first terminal device; The first terminal device enters the CS domain to wait for a call or the first terminal device activates the long term evolution LTE capability; The first terminal device receives a second call request; wherein, the second call request is a call request in the CS domain, and the second call request is initiated after determining that the first terminal device completes CS domain registration or location update; or, the second call request is a call request in the IMS domain, and the second call request is initiated after determining that the first terminal device has enabled LTE capability; or, the second call request is initiated by the second network device to the first terminal device through the CS domain or IMS domain after the timer expires.

24. The method according to claim 23, wherein Before the first terminal device enters the CS domain to wait for a call, the method further includes: The first terminal device sends an IMS deregistration request.

25. The method according to claim 23, wherein The first condition also includes that the network does not support switching from NG-RAN to UTRAN.

26. The method according to any one of claims 23 to 25, characterized in that The first message carries third information, and the third information is used by the second network device to carry the second information when sending a first request to the third network device; the first request is used to request that the call be routed to the first terminal device through the CS domain, and the second information is used by the third network device to send the first information to the second network device after determining that the first terminal device has completed CS domain registration or location update.

27. The method according to any one of claims 23 to 25, characterized in that The first message carries seventh information, and the seventh information is used by the second network device to carry the fifth information when sending a first request to the third network device; the first request is used to request fourth information, and the fourth information is used to determine whether a call can be made to the first terminal device through the IMS domain; The fifth information is used by the third network device to carry the sixth information when sending a second request to the fourth network device, the second request is used to request the fourth information, and the sixth information is used by the fourth network device to send the fourth information to the third network device after determining that the first terminal device has enabled the long-term evolution LTE capability.

28. The method according to any one of claims 23 to 25, characterized in that The first message also carries a timer, and the timer is used by the second network device to initiate a call to the first terminal device through the CS domain or the IMS domain when the timer expires.

29. The method according to any one of claims 23 to 25, wherein: The first terminal device enters the CS domain and waits for a call, including: The first terminal device reselects to a second generation mobile communication technology 2G network or a third generation mobile communication technology 3G network; The first terminal device sends an attach request or a location update request to a mobile switching center MSC; The first terminal device waits for a call in the CS domain.

30. The method according to any one of claims 23 to 25, characterized in that After the first terminal device enters the CS domain and waits for a call, the first terminal device receives a second call request, including: The first terminal device receives a second call request in the CS domain.

31. The method according to any one of claims 23 to 25, wherein: After the first terminal device enables the LTE capability, the first terminal device receives a second call request, including: The first terminal device sends a registration request to the fourth network device, where the registration request carries a long term evolution (LTE) capability; The first terminal device receives a second call request in the IP Multimedia System IMS domain.

32. A call processing method, characterized in that: The method comprises: The second network device sends a first call request to the first terminal device through the IP Multimedia System IMS domain; The second network device receives a first message sent by the first terminal device, where the first message carries an identifier of the first terminal device, and the first message is used to request redirecting the first call request to the first terminal device; The second network device sends a second call request to the first terminal device through the CS domain or the IMS domain; the second call request is a call request in the CS domain, and the second call request is initiated after determining that the first terminal device completes the CS domain registration or location update; or, the second call request is a call request in the IMS domain, and the second call request is initiated after determining that the first terminal device has turned on the LTE capability; or, the second call request is initiated by the second network device to the first terminal device through the CS domain or the IMS domain after the timer expires.

33. The method according to claim 32, characterized in that Before the second network device sends a second call request to the first terminal device through the CS domain, the method further includes: The second network device receives the IMS deregistration request sent by the first terminal device.

34. The method according to claim 32, wherein The second network device sending a second call request to the first terminal device through the CS domain includes: The second network device sends a first request to the third network device, where the first request is used to request first information that the call is routed to the first terminal device through the CS domain; The second network device receives the first information sent by the third network device; The second network device sends a second call request to the first terminal device through the CS domain based on the first information.

35. The method according to claim 34, wherein The first request carries second information, and the method further includes: The third network device sends the first information to the second network device after determining that the first terminal device completes CS domain registration or location update based on the second information.

36. The method according to claim 35, characterized in that The first message carries third information, and the third information is used by the second network device to carry the second information when sending the first request to the third network device.

37. The method according to claim 32, wherein The second network device sending a second call request to the first terminal device through the IMS domain includes: The second network device sends a first request to the third network device, where the first request is used to request fourth information, and the fourth information is used to determine whether a call can be made to the first terminal device through the IMS domain; The second network device receives the fourth information sent by the third network device; If the second network device determines that it is impossible to call the first terminal device through the IMS domain based on the fourth information, the second network device sends a second call request to the first terminal device through the IMS domain.

38. The method according to claim 37, wherein The first request carries fifth information, and the method further includes: The third network device sends a second request carrying sixth information to the fourth network device based on the fifth information, where the second request is used to request the fourth information; The fourth network device sends the fourth information to the third network device after determining that the first terminal device has enabled the Long Term Evolution (LTE) capability based on the sixth information; The third network device sends the fourth information to the second network device.

39. The method according to claim 38, characterized in that The first message carries seventh information, and the seventh information is used by the second network device to carry the fifth information when sending the first request to the third network device.

40. The method according to claim 34 or 37, characterized in that The first message includes a timer; The second network device sending a first request to the third network device includes: When the timer times out, the second network device sends a first request to the third network device.

41. A communication device, characterized in that The method comprises a processor, a memory, and a transceiver, wherein the processor and the memory are coupled, the transceiver is used to transmit and receive data, the processor is used to implement the method according to any one of claims 1 to 6, or the processor is used to implement the method according to any one of claims 21 to 22, or the processor is used to implement the method according to any one of claims 23 to 31.

42. A chip, characterized in that: comprising a processor and an interface, wherein the processor and the interface are coupled; The interface is used to receive or output signals, and the processor is used to execute code instructions so that the method of any one of claims 1 to 6 is executed, or the method of any one of claims 21 to 22 is executed, or the method of any one of claims 23 to 31 is executed.

43. A communication system, characterized in that The communication system includes a first terminal device and a network device, the first terminal device is used to execute the method described in any one of claims 1 to 6; the network device is used to execute the method described in any one of claims 7 to 15, or the network device is used to execute the method described in any one of claims 16 to 20, or the network device is used to execute the method described in any one of claims 21 to 22.

44. A communication system, characterized in that The communication system includes a first terminal device and a network device, wherein the first terminal device is used to execute the method described in any one of claims 23 to 31; and the network device is used to execute the method described in any one of claims 32 to 40.

45. A computer-readable storage medium, characterized in that The computer-readable storage medium stores computer-executable instructions, which, when called by the computer, are used to cause the computer to execute the method described in any one of claims 1 to 6, or, when called by the computer, are used to cause the computer to execute the method described in any one of claims 21 to 22, or, when called by the computer, are used to cause the computer to execute the method described in any one of claims 23 to 31.

46. ​​A computer program product, characterized in that Used to store computer software instructions, when the instructions are executed by the communication device, to implement the method of any one of claims 1 to 6, or the method of any one of claims 21 to 22, or the method of any one of claims 23 to 31.

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