Method and device for call connection

Abstract

The invention provides a method and a device for call connection, which can be applied to a scene that a called terminal falls back to an LTE (Long Term Evolution) system from an NR (Noise Ratio) system by adopting an EPSFB in a called process. The method is applied to a called terminal and comprises the following steps: the called terminal receives an update message; receiving a switching instruction; switching from the NR system to the LTE system according to the switching instruction; after the update message is received and before the TAU is updated in the tracking area, a first response message is sent, the first response message carries a first parameter, and the first parameter indicates that a voice bearer is not established between the called terminal and the called core network equipment; and sending the ringing message. In the application, the called terminal does not need to wait for the completion of the TAU to send the first response message, and the message disorder problem that the ringing message arrives earlier than the first response message is avoided by sending the first response message in advance, so that the calling core network equipment can smoothly forward the voice packets transmitted between the calling side and the called side, and the user experience is improved. And the silent conversation probability is reduced.

Description

Method and device for call connection

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office on December 30, 2022, with application number 202211737088.6 and application name “A method and device for call connection”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of voice calls, and in particular, to a method and apparatus for call connection. Background Art

[0003] The Session Initiation Protocol (SIP), an application-layer control protocol for multimedia communications over IP networks, was proposed by the Internet Engineering Task Force (IETF). The calling and called terminals can communicate using SIP messages or signaling during the call establishment process.

[0004] During the process of establishing a call connection between the calling terminal and the called terminal, the called terminal may fall back from the new radio (NR) standard to the long term evolution (LTE) standard during the called process. When the terminal falls back from the NR standard to the LTE standard, the called terminal will send a 200OK message to the calling terminal through the network. During the short period of time when the called terminal sends the 200OK message to the calling terminal through the network, the called terminal will also send a 180Ringing message to the calling terminal through the network. In this case, the problem of silence after the call often occurs, affecting the user's call experience.

[0005] Summary of the Invention

[0006] In view of this, the present application provides a method, apparatus, computer-readable storage medium, and computer program product for call connection, which reduce the probability of silent calls.

[0007] In a first aspect, a method for call connection is provided, the method being applied to a called terminal, the method comprising:

[0008] receiving a session invitation from a calling terminal, wherein the session invitation is used to request to establish a voice call with the called terminal;

[0009] Sending a request response message to the calling terminal, where the request response message is a response to the session invitation and is used to indicate that the called terminal has received the session invitation;

[0010] Receive update messages from the called core network device;

[0011] receiving a switching instruction, wherein the switching instruction is used to notify the called terminal to switch from the first communication standard to the second communication standard;

[0012] Switching from the first communication standard to the second communication standard according to the switching instruction;

[0013] After receiving the update message and before completing the tracking area update (TAU), sending a first response message, where the first response message is a response to the update message, the first response message is used to indicate that the called terminal has received the update message, and the first response message carries a first parameter, where the first parameter indicates that no voice bearer has been established between the called terminal and the called core network device;

[0014] After the called terminal sends the first response message, the called terminal sends a ringing message, where the ringing message is used to notify the calling terminal that the called terminal has started ringing.

[0015] The above technical solution is executed by the called terminal or the chip in the called terminal. Based on the above solution, compared to the called terminal waiting for the TAU to be completed before sending the first response message, the called terminal does not need to wait for the TAU to be completed before sending the first response message, so that the time interval between the time the called terminal sends the first response message and the time interval between the ringing message is longer, that is, the time interval between the time the called terminal sends the first response message and the time interval between the ringing message in the embodiment of the present application is greater than the time interval between the time the called terminal sends the first response message and the time interval between the ringing message in the prior art. In this way, although no voice bearer is created between the called terminal and the called core network device when the first response message is sent, since the sending time of the first response message is advanced, the time when the first response message arrives at the calling core network device will also be earlier than the ringing message, avoiding the message disorder problem caused when the ringing message arrives earlier than the first response message, so that the calling core network device can smoothly forward the voice packet on the called side, reducing the probability of silent calls.

[0016] It should be noted that the "calling core network device" in this article may refer to the core network device of the calling party's home location, and the "called core network device" may refer to the core network device of the called party's home location.

[0017] In some possible implementations, sending the first response message after receiving the update message and before the tracking area update TAU is completed includes: the called terminal sends the first response message after receiving the switching indication and switching from the first communication standard to the second communication standard, and before the tracking area update TAU is completed.

[0018] In some possible implementations, after the called terminal sends the first response message and before sending the ringing message, the method further includes:

[0019] receiving a voice bearer establishment message from a called core network device, wherein the voice bearer establishment message is used to request establishment of a voice bearer under the second communication standard with the called terminal;

[0020] Establishing a voice bearer with the called terminal according to the voice bearer establishment message;

[0021] A voice bearer establishment completion message is sent to the called core network device, where the voice bearer establishment completion message is used to indicate that a voice bearer has been established between the called terminal and the called core network device.

[0022] Therefore, before sending the ringing message, the called terminal can first establish a bearer with the called core network device to prepare for the subsequent call connection.

[0023] In some possible implementations, after sending the first response message, the method further includes:

[0024] Sending a first request message, where the first request message is used to request updating of a tracking area;

[0025] receiving a TAU accept message from the called core network device, where the TAU accept message is used to respond to the first request message;

[0026] A TAU completion message is sent to the called core network device, where the TAU completion message indicates that the tracking area update process is completed.

[0027] Therefore, after sending the first response message, the called terminal can continue to complete the tracking area update process so as to fall back to the second communication standard (such as the LTE standard).

[0028] Optionally, the first response message is a 200OK message.

[0029] Optionally, the value of the first parameter is local none.

[0030] In a second aspect, a method for call connection is provided, the method being applied to a called core network device, the method comprising:

[0031] The called core network device sends a session invitation to the called terminal, where the session invitation is used to request to establish a voice call with the called terminal;

[0032] The called core network device receives a request response message sent by the called terminal, where the request response is a response to the session invitation and is used to indicate that the called terminal has received the session invitation message;

[0033] The called core network device forwards the request response message to the calling core network device;

[0034] The called core network device sends an update message to the called terminal;

[0035] Sending a switching instruction to the called terminal, wherein the switching instruction is used to notify the called terminal to switch from the first communication standard to the second communication standard;

[0036] After sending the handover indication to the called terminal and before the called terminal completes initiating a tracking area update (TAU), receiving a first response message from the called terminal, the first response message being used to indicate that the called terminal has received the update message, the first response message carrying a first parameter indicating that no voice bearer has been established between the called terminal and the called core network device;

[0037] Sending the first response message to the calling core network device;

[0038] receiving a ringing message from a called terminal, wherein the ringing message is used to notify the calling terminal that the called terminal has started ringing;

[0039] The ringing message is sent to the calling core network device.

[0040] The above technical solution is executed by the called core network device or a chip in the called core network device. Based on the above solution, the called core network device can forward the first response message sent by the called terminal before the TAU to the calling core network device. This ensures that the first response message arrives at the calling core network device before the ringing message, avoiding the message out-of-order problem caused by the ringing message arriving before the first response message. This allows the calling core network device to smoothly forward the voice packets from the called side, reducing the probability of silent calls.

[0041] In some possible implementations, before receiving a ringing message from the called terminal, the method further includes:

[0042] Send a voice bearer establishment message to the called terminal;

[0043] A voice bearer establishment completion message is received from the called terminal, where the voice bearer establishment completion message is used to indicate that a voice bearer has been established between the called terminal and the called core network device.

[0044] In some possible implementations, after receiving the first response message, the method further includes:

[0045] receiving a first request message from a called terminal, where the first request message is used to request updating a tracking area;

[0046] Sending an acceptance message to the called terminal, where the acceptance message is used to respond to the first request message;

[0047] A tracking area update completion message is received from the called terminal, where the tracking area update completion message indicates that a tracking area update process has been completed.

[0048] In a third aspect, a method for call connection is provided, the method being applied to a calling core network device, the method comprising:

[0049] The calling core network device sends a session invitation to the called core network device, wherein the session invitation is used to request to establish a voice call with the called terminal;

[0050] The calling core network device receives a request response message from the called core network device, where the request response message is a response to the session invitation and is used to indicate that the called terminal has received the session invitation;

[0051] receiving an update message sent by the calling terminal, and sending the update message to the called core network device;

[0052] receiving a first response message from the called core network device, the first response message being used to indicate that the called terminal has received the update message, the first response message carrying a first parameter indicating that no voice bearer has been established between the called terminal and the called core network device;

[0053] Closing the media forwarding port according to the first parameter;

[0054] receiving a ringing message from a called core network device, wherein the ringing message is used to notify the calling terminal that the called terminal has started ringing;

[0055] Opening a media forwarding port according to the ringing message;

[0056] The ringing message is sent to the calling terminal.

[0057] The above technical solution is executed by the calling core network device or a chip within the calling core network device. Based on this solution, the first response message arrives at the calling core network device before the ringing message, avoiding the message out-of-order issue that occurs when the ringing message arrives before the first response message. This allows the calling core network device to smoothly forward the called party's voice packets, reducing the likelihood of silent calls.

[0058] In a fourth aspect, a method for call connection is provided, the method being applied to a calling terminal, the method comprising:

[0059] The calling terminal sends a session invitation to the calling core network device, wherein the session invitation is used to request to establish a voice call with the called terminal;

[0060] The calling terminal receives a request response message forwarded by the calling core network device, where the request response is a response to the session invitation and is used to indicate that the called terminal has received the session invitation message;

[0061] The calling terminal sends an update message to the calling core network device;

[0062] The calling terminal receives a first response message from the calling core network device, where the first response message is used to indicate that the called terminal has received the update message, and the first response message carries a first parameter, where the first parameter indicates that no voice bearer has been established between the called terminal and the called core network device.

[0063] The calling terminal receives a ringing message from the calling core network device, where the ringing message is used to notify the calling terminal that the called terminal has started ringing.

[0064] The above technical solution is executed by the calling terminal or the chip in the calling terminal. Based on this solution, the first response message arrives at the calling core network device before the ringing message, avoiding the message out-of-order problem that occurs when the ringing message arrives before the first response message. This allows the calling core network device to smoothly forward the voice packets from the called party, allowing the calling terminal to receive the voice packets from the called terminal and reducing the probability of silent calls.

[0065] In a fifth aspect, a call method is provided, which is applied to a called terminal and includes:

[0066] receiving a session invitation from a calling terminal, wherein the session invitation is used to request to establish a voice call with the called terminal;

[0067] Sending a request response message to the calling terminal, where the request response message is a response to the session invitation and is used to indicate that the called terminal has received the session invitation;

[0068] Receive update messages from the called core network device;

[0069] After receiving the update message, starting a first timer;

[0070] The called terminal receives a switching instruction within the first timer, where the switching instruction is used to notify the called terminal to switch from the first communication standard to the second communication standard;

[0071] The called terminal switches from the first communication standard to the second communication standard according to the switching instruction;

[0072] Within the first timer, the called terminal receives a voice bearer establishment message from the called core network device after switching from the first communication standard to the second communication standard, and after receiving the voice bearer establishment message, a voice bearer is established between the called terminal and the called core network device, the called terminal sends a second response message to the core network device, where the second response message is a response to the update message, the second response message is used to indicate that the called terminal has received the update message, the second response message carries a second parameter, the second parameter indicates that a voice bearer has been established between the called terminal and the core network, and the voice bearer establishment message is used to request to establish a voice bearer under the second communication standard with the called terminal;

[0073] After the called terminal sends the second response message, the called terminal sends a ringing message, where the ringing message is used to notify the calling terminal that the called terminal has started ringing.

[0074] The above technical solution is executed by the called terminal or the chip in the called terminal. Based on the above solution, after receiving the update message of the called core network device, the called terminal starts the first timer and then detects whether the voice bearer establishment message from the called core network device is received within the first timer. If the voice bearer establishment message from the called core network device is received within the first timer, the called terminal sends a second response message (such as a 200OK message) to the called core network device, and carries a second parameter in the second response message. The second parameter indicates that the called terminal and the called core network device have established a voice bearer. Compared with the situation where the second response message is sent without waiting for the voice bearer to be established, the embodiment of the present application sets a timer to wait for the voice bearer to be established. If the voice bearer is established during the operation of the timer, the calling core network device can smoothly forward the voice packet, thereby reducing the probability of silent calls.

[0075] Optionally, the value of the second parameter is local sendrecv.

[0076] Optionally, the duration of the first timer is greater than a first time threshold and less than a second time threshold, and the second time threshold is related to the duration of a timer related to establishing a voice bearer on the called core network side.

[0077] Exemplarily, the duration of the first timer is smaller than the duration of the timer on the called core network side.

[0078] In some possible implementations, the method further includes:

[0079] receiving, within the first timer, a voice bearer establishment message from a called core network device;

[0080] Within the first timer, a voice bearer establishment completion message is sent to the called core network device.

[0081] In some possible implementations, the method further includes:

[0082] In response to the called terminal not receiving a voice bearer establishment message from the called core network device within the first timer, the called terminal sending a third response message to the called core network device, where the third response message is a response to the update message, the third response message is used to indicate that the called terminal has received the update message, and the third response message carries a first parameter, where the first parameter indicates that no voice bearer has been established between the called terminal and the called core network device;

[0083] After sending the third response message, a ringing message is sent to the called core network device, where the ringing message is used to notify the calling terminal that the called terminal has started ringing.

[0084] In some possible implementations, after sending the third response message to the called core network device and before sending the ringing message to the called core network device, the method further includes:

[0085] Receive a voice bearer establishment message from the called core network device;

[0086] Send a voice bearer establishment completion message to the called core network device.

[0087] For example, if the called terminal does not receive a voice bearer establishment message from the called core network device within the first timer, it will then send a 200OK message to the called core network device after the first timer expires. Furthermore, the called terminal must wait for the voice bearer to be established before sending a 180Ringing message to the called core network device. This increases the time interval between the 200OK and 180Ringing messages, reducing call out-of-order and call silence issues caused by a short time interval, and improving the user experience.

[0088] Optionally, the value of the first parameter is local none.

[0089] Optionally, the value of the second parameter is local sendrecv.

[0090] In a sixth aspect, a call method is provided, the method being applied to a called core network device, the method comprising:

[0091] The called core network device sends a session invitation to the called terminal, where the session invitation is used to request to establish a voice call with the called terminal;

[0092] The called core network device receives a request response message sent by the called terminal, where the request response is a response to the session invitation and is used to indicate that the called terminal has received the session invitation message;

[0093] The called core network device forwards the request response message to the calling core network device;

[0094] Send an update message to the called terminal;

[0095] receiving a second response message from the called terminal, the second response message carrying a second parameter, the second parameter indicating that a voice bearer has been established between the called terminal and the core network, wherein the second response message is sent by the called terminal when the called core network device sends a voice bearer establishment message to the called terminal within the first timer;

[0096] Sending the second response message to the calling core network device;

[0097] receiving a ringing message from the called terminal, where the ringing message is used to notify the calling terminal that the called terminal has started ringing;

[0098] The ringing message is sent to the calling core network device.

[0099] The above technical solution is executed by the called core network device or a chip in the called core network device. Based on the above solution, if the called core network device sends a voice bearer establishment message to the called terminal within the first timer, then after receiving the second response message (such as a 200OK message), the called core network device can forward the second response message to the calling core network device. The second response message carries a second parameter, which indicates that a voice bearer has been established between the called terminal and the called core network device. The second parameter can enable the calling core network device to open the media forwarding port according to the second parameter, thereby smoothly forwarding voice packets and reducing the probability of silent calls.

[0100] For the relevant description of the first timer, please refer to the introduction in the fifth aspect and will not be repeated here.

[0101] In some possible implementations, the method further includes:

[0102] Sending a voice bearer establishment message to the called terminal within the first timer;

[0103] Within the first timer, a voice bearer establishment completion message is received from the called terminal.

[0104] In one possible implementation, if the called core network device does not send a voice bearer establishment message within the first timer, the method further includes: receiving a third response message from the called terminal, the third response message carrying a first parameter, the first parameter indicating that a voice bearer is not established between the called terminal and the called core network device;

[0105] Sending a third response message to the calling core network device;

[0106] The receiving of the ringing message includes:

[0107] After the voice bearer between the called terminal and the called core network device is established, a ringing message from the called terminal is received.

[0108] In one possible implementation, if the called core network device does not send a voice bearer establishment message within the first timer, the method further includes: sending a voice bearer establishment message to the called terminal before receiving a ringing message from the called terminal; and receiving a voice bearer establishment completion message from the called terminal.

[0109] In a seventh aspect, a call method is provided, the method being applied to a calling core network device, the method comprising:

[0110] The calling core network device sends a session invitation to the called core network device, wherein the session invitation is used to request to establish a voice call with the called terminal;

[0111] The calling core network device receives a request response message from the called core network device, where the request response is a response to the session invitation and is used to indicate that the called terminal has received the session invitation message;

[0112] The calling core network device receives the update message from the calling terminal and sends the update message to the called core network device;

[0113] The calling core network device receives a second response message from the called core network device, and sends the second response message to the calling terminal, where the second response message carries a second parameter, and the second parameter indicates that a voice bearer has been established between the called terminal and the core network. The second response message is sent by the called terminal when the voice bearer establishment message from the called core network device is received within the first timer.

[0114] The calling core network device opens the media forwarding port according to the second parameter;

[0115] The calling core network device receives the ringing message from the called core network device and sends the ringing message to the calling terminal, where the ringing message is used to notify the calling terminal that the called terminal has started ringing.

[0116] The above technical solution is executed by the calling core network device or the chip in the calling core network device. Based on the above solution, after receiving the second response message, the calling terminal opens the media forwarding port according to the second parameter, which can smoothly forward the voice packets of the called party, reducing the probability of silent calls.

[0117] In one possible implementation, if the called core network device does not send a voice bearer establishment message within the first timer, the method further includes: receiving a third response message from the called core network device, the third response message carrying a first parameter, the first parameter indicating that a voice bearer is not established between the called terminal and the called core network device;

[0118] Closing the media forwarding port according to the first parameter;

[0119] The method further includes: after receiving the ringing message, opening a media forwarding port according to the ringing message.

[0120] Here, even if the calling core network device closes the media forwarding port according to the third response message, it will open the media forwarding port based on the ringing message after receiving the ringing message, so as to smoothly forward the voice packet of the called side and reduce the probability of silent call.

[0121] In an eighth aspect, a call method is provided, the method being applied to a calling terminal, the method comprising:

[0122] The calling terminal sends a session invitation to the calling core network device, wherein the session invitation is used to request to establish a voice call with the called terminal;

[0123] The calling terminal receives a request response message forwarded by the calling core network device, where the request response is a response to the session invitation and is used to indicate that the called terminal has received the session invitation message;

[0124] The calling terminal sends an update message to the calling core network device;

[0125] The calling terminal receives a second response message from the calling core network device, where the second response message carries a second parameter, where the second parameter indicates that a voice bearer has been established between the called terminal and the core network, wherein the second response message is sent by the called terminal when the voice bearer establishment message from the called core network device is received within the first timer;

[0126] The calling terminal receives a ringing message from the calling core network device, where the ringing message is used to notify the calling terminal that the called terminal has started ringing.

[0127] The above technical solution is executed by the calling terminal or a chip in the calling terminal. Based on this solution, after the second response message reaches the calling core network device, the calling core network device opens the media forwarding port based on the second parameter. This enables the calling core network device to smoothly forward the voice packets from the called party, allowing the calling terminal to receive the voice packets from the called terminal, reducing the probability of silent calls.

[0128] Alternatively, in one possible implementation, if the called core network device does not send a voice bearer establishment message within the first timer, the method also includes: receiving a third response message from the calling core network device, the third response message carrying a first parameter, and the first parameter indicating that the called terminal and the called core network device have not established a voice bearer.

[0129] In a ninth aspect, an electronic device is provided, comprising a unit for executing any one of the methods of the first, fourth, fifth, and eighth aspects. The electronic device may be a terminal or a chip within a terminal. The electronic device includes an input unit, a display unit, and a processing unit.

[0130] When the electronic device is a terminal, the processing unit may be a processor, the input unit may be a communication interface, and the display unit may be a graphics processing module and a screen; the terminal may also include a memory for storing computer program code, and when the processor executes the computer program code stored in the memory, the terminal executes any one of the methods in the first aspect, or the terminal executes any one of the methods in the fourth aspect, or the terminal executes any one of the methods in the fifth aspect, or the terminal executes any one of the methods in the first aspect, or the terminal executes any one of the methods in the eighth aspect.

[0131] When the electronic device is a chip in a terminal, the processing unit may be a logic processing unit inside the chip, the input unit may be an input interface, pin or circuit, etc., and the display unit may be a graphics processing unit inside the chip; the chip may also include a memory, which may be a memory inside the chip (for example, a register, a cache, etc.) or a memory located outside the chip (for example, a read-only memory, a random access memory, etc.); the memory is used to store computer program code, and when the processor executes the computer program code stored in the memory, the chip executes any one of the methods in the first aspect, or the terminal executes any one of the methods in the fourth aspect, or the terminal executes any one of the methods in the fifth aspect, or the terminal executes any one of the methods in the first aspect, or the terminal executes any one of the methods in the eighth aspect.

[0132] In a tenth aspect, a device for call connection is provided, the device comprising a unit for executing any one of the methods of aspects 2, 3, 6, and 7. The electronic device may be a core network device or a chip within the core network device.

[0133] In the eleventh aspect, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores a computer program code, and when the computer program code is executed by a device for call connection, the transposition executes any one of the methods in the first to eighth aspects.

[0134] In a twelfth aspect, a computer program product is provided, comprising: a computer program code, which, when executed by a device for call connection, enables the device to execute any one of the methods in the first to eighth aspects.

[0135] In a thirteenth aspect, embodiments of the present application provide a chip system, comprising one or more processors configured to retrieve and execute instructions stored in a memory, thereby executing the method of each of the above aspects or any possible implementation of each aspect. The chip system may be composed of a chip or may include a chip and other discrete devices.

[0136] Among them, the chip system may include an input circuit or interface for sending information or data, and an output circuit or interface for receiving information or data.

[0137] In a fourteenth aspect, a communication system is provided, comprising one or more of the aforementioned called terminal, calling terminal, called core network device, and calling core network device. Optionally, the communication system may further include other devices that communicate with the aforementioned devices (e.g., calling access network device, called access network device). BRIEF DESCRIPTION OF THE DRAWINGS

[0138] FIG1 is a diagram illustrating an example scenario of a communication system using an embodiment of the present application;

[0139] FIG2 is an example diagram of a portion of the process where messages are not out of order when a calling terminal and a called terminal establish a call connection;

[0140] 3 is an example diagram of a portion of the process where messages are out of order when the calling terminal and the called terminal establish a call connection;

[0141] FIG4 is a schematic flow chart of a method for call connection according to an embodiment of the present application;

[0142] FIG5 is a schematic flow chart of a method for call connection according to an embodiment of the present application;

[0143] FIG6 is an example diagram of a call connection according to an embodiment of the present application;

[0144] FIG7 is a schematic flowchart of a method for call connection according to another embodiment of the present application;

[0145] FIG8 is a schematic flow chart of a method for call connection according to another embodiment of the present application;

[0146] FIG9 is an example diagram of a call connection according to another embodiment of the present application;

[0147] FIG10 is an exemplary block diagram of an apparatus for call connection according to an embodiment of the present application;

[0148] FIG11 is a schematic structural diagram of an electronic device used in an embodiment of the present application. DETAILED DESCRIPTION

[0149] The technical solutions in the embodiments of the present application will be described below with reference to the accompanying drawings.

[0150] In the embodiments of the present application, unless otherwise specified, “a plurality of” may mean two or more.

[0151] The technical solutions of the embodiments of the present application can be applied to various communication systems, such as: long term evolution (LTE) system, universal mobile telecommunication system (UMTS), world-wide interoperability for microwave access (WiMAX) communication system, fifth generation (5G) system or new radio (NR) and future mobile communication systems, vehicle-to-X (V2X), where V2X may include vehicle-to-network (V2N), vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), vehicle-to-pedestrian (V2P), etc., long term evolution technology for vehicle communication (LTE-V), Internet of Vehicles, machine type communication (MTC), Internet of Things (IoT), long term evolution technology for machine-to-machine communication (LTE-M), machine-to-machine (M2M), etc.

[0152] The embodiment of the present application is applied to a scenario where a terminal falls back from a first communication standard to a second communication standard during a call. The first communication standard and the second communication standard are different. The embodiment of the present application does not specifically limit the first communication standard and the second communication standard.

[0153] Exemplarily, the first communication standard may be the NR standard, and the second communication standard may be the LTE standard.

[0154] The interaction process of the embodiment of the present application can be applied to the Session Initiation Protocol (SIP), which is a signaling protocol used to control the initiation, modification, and termination of interactive multimedia sessions.

[0155] The following is a brief introduction to some messages in the SIP protocol.

[0156] The session invitation message (Invite) is used to initiate a session request. The session invitation message can be initiated by the calling terminal.

[0157] Update messages are used to initiate update requests. Update messages are typically used for media updates. Update messages can be initiated by the calling terminal.

[0158] The PRACK message is used to acknowledge a provisional reliability response, confirming receipt of a 1XX provisional response. The PRACK message is typically used to acknowledge a 183 message during session establishment and to provide a second SDP offer for media resource negotiation.

[0159] The ACK message confirms receipt of the final response to the Invite request. After receiving the 200 (OK) final response from the called party, the caller sends an ACK message to the called party to confirm receipt of the final response, completing the three-way handshake consisting of the Invite, 200, and ACK messages. The ACK message is used only in conjunction with the Invite message.

[0160] The BYE request ends the current session. Upon receiving a BYE request, the current dialog session is terminated. A BYE request can only be sent within an established dialog (established via an Invite request). The caller can terminate a session by sending a BYE request in both an Early Dialog and a Confirmed Dialog. The callee can terminate a session only in a Confirmed Dialog.

[0161] Activate Dedicated EPS Bearer Context Request: This message is sent by the network to the UE to request the activation of a dedicated evolved packet switched system (EPS) bearer context. The dedicated bearer has the same PDN address and APN as the activated default EPS bearer context.

[0162] Activate Dedicated EPS Bearer Context Accept: This message is sent by the UE to the network to confirm the activation of a default bearer context.

[0163] Tracking Area Update Request: The actual tracking area registration update of the UE in the network.

[0164] Tracking Area Update Accept: The network sends this message to the UE to provide EPS mobility management related data in response to the Tracking Area Update Request message.

[0165] Tracking Area Update Complete: If the globally unique temporary UE identity (GUTI) has been changed or a new temporary mobile subscriber identity (TMSI) has been assigned, the UE sends this message to the network in response to the Tracking Area Update Accept message.

[0166] RRC: Radio Resource Control (RRC), the radio resource control protocol RRC layer controls the allocation of radio resources and sends related signaling.

[0167] RRCConnectionReconfiguration: RRC reconfiguration message, used for allocation of radio resources.

[0168] MeasurementReport: used to report wireless measurement results.

[0169] RRC Release: used to release radio resources.

[0170] MobilityFromNRCommand: The network uses this command to inform the terminal to switch from the NR network to the LTE network.

[0171] SIP response messages are used to respond to request messages, indicating the success or failure of a call. Different types of response messages are distinguished by status codes. Status codes typically consist of three integers. The first digit of the status code defines the response type, while the remaining two digits provide further details about the response.

[0172] SIP protocol response messages are classified as follows:

[0173] 1xx: Information response (call progress response), indicating that the request message has been received and is being processed.

[0174] For example, the 100Trying message is used to try a call, and the 180Ringing message is a ringing message.

[0175] 2xx: Successful response, indicating that the request has been successfully accepted or processed. For example, the 200 OK (Invite) message is used to indicate that the Invite request has been successfully accepted or processed.

[0176] 3xx: Redirection response, indicating that further action is required to complete the request.

[0177] 4xx: Client error, indicating that the request message contains a syntax error or the SIP server cannot complete the processing of the request message.

[0178] 5xx: Server error, indicating that the SIP server fails and cannot process the correct message.

[0179] 6xx: Global failure, indicating that the request cannot be implemented on any SIP server.

[0180] It should be understood that the above-mentioned description of messages in the SIP protocol is merely an example description, and the embodiments of the present application are not limited thereto. FIG1 is a diagram illustrating a scenario of a communication system using an embodiment of the present application. As shown in FIG1 , the communication system includes a calling terminal, a calling wireless access network device, a calling core network device, a called terminal, a called wireless access network device (NR), a called wireless access network device (LTE), and a called core network device. The calling terminal and the called terminal can establish a call connection.

[0181] In the 3rd Generation Partnership Project (3GPP), 5G mobile communication networks can continue to use the voice architecture of 4G mobile communication networks and still provide voice services based on the IP multimedia subsystem (IMS). The radio access technology of 4G mobile communication networks is long term evolution (LTE), and the voice call service carried by LTE is called voice on LTE (VoLTE). The radio access technology of 5G mobile communication networks can be called NR, and the voice call service carried by NR is called voice on NR (VoNR). VoNR is the ultimate voice service solution for 5G. If 5G does not have the conditions for VoNR, 5G NR may not be able to provide voice services. In this case, voice services need to be implemented based on VoLTE. That is, when a terminal residing on NR initiates a call, it needs to fall back to 4G through the evolved packet switched system (EPS) fallback (FB) and use VoLTE to carry voice services. EPS FB means that if 5G does not meet the requirements for VoNR, voice services will fall back from 5G to 4G (i.e., switching from NR to LTE), relying on VoLTE to ensure voice service continuity. Therefore, VoLTE and VoNR will exist as different access methods for 5G IMS voice services.

[0182] For example, for the called terminal, there may be a scenario where it switches from NR to LTE during the communication process, that is, it falls back from the NR EPS FB to the LTE standard. As shown in Figure 1, when the called terminal resides in the NR access network, if 5G does not meet the VoNR conditions, the voice service of the called terminal is switched from the NR standard to the LTE standard. That is, the called terminal can switch to the LTE access network to ensure service continuity.

[0183] For unified explanation here, the "calling core network device" in this application may refer to the core network device of the calling party's home location, and the "called core network device" may refer to the core network device of the called party's home location.

[0184] Whether on the calling or called side, the terminal connects to the access network equipment wirelessly, and the wireless access network equipment connects to the core network equipment wirelessly or wired. The core network equipment and the wireless access network equipment can be independent and distinct physical devices, or they can integrate the core network equipment's functions and the wireless access network equipment's logical functions into the same physical device, or a single physical device can integrate some of the core network equipment's functions and some of the wireless access network equipment's functions. Terminal equipment can be fixed or mobile.

[0185] It should be understood that Figure 1 is only a schematic diagram of the architecture of the communication system, and the communication system may also include other network devices, such as wireless relay devices and wireless backhaul devices, which are not shown in Figure 1. The embodiments of the present application do not limit the number of core network devices, wireless access network devices, and terminals included in the mobile communication system.

[0186] The terminal may also be referred to as: terminal device, user equipment (UE), mobile station (MS), mobile terminal (MT), access terminal, user unit, user station, mobile station, mobile station, remote station, remote terminal, mobile device, user terminal, terminal, wireless communication device, user agent or user device, etc.

[0187] A terminal can be a device that provides voice / data connectivity to a user, such as a handheld device or vehicle-mounted device with wireless connection function. At present, some examples of terminals include: mobile phones, tablet computers, laptop computers, PDAs, mobile internet devices (MIDs), wearable devices, virtual reality (VR) devices, augmented reality (AR) devices, wireless terminals in industrial control, wireless terminals equipped with cloud games, wireless terminals in self-driving cars, wireless terminals in remote medical surgery, wireless terminals in smart grids, wireless terminals in transportation safety, wireless terminals in smart cities, wireless terminals in smart homes, cellular phones, cordless phones, session initiation protocol (SIP) phones, wireless local loop (WLL) stations, personal digital assistants (PDAs), handheld devices with wireless communication capabilities, computing devices or other processing devices connected to wireless modems, vehicle-mounted devices, wearable devices, terminal devices in 5G networks or future evolved public land mobile communication networks (PLMNs). The terminal equipment in the network (PLMN), etc., is not limited to this in the embodiments of the present application.

[0188] As an example and not a limitation, in the embodiment of the present application, the terminal may also be a wearable device. Wearable devices may also be called wearable smart devices, which are a general term for wearable devices that are intelligently designed and developed using wearable technology for daily wear, such as glasses, gloves, watches, clothing, and shoes. A wearable device is a portable device that is worn directly on the body or integrated into the user's clothes or accessories. Wearable devices are not only hardware devices, but also achieve powerful functions through software support, data interaction, and cloud interaction. Broadly speaking, wearable smart devices include those that are fully functional, large in size, and can achieve complete or partial functions without relying on smartphones, such as smart watches or smart glasses, as well as those that only focus on a certain type of application function and need to be used in conjunction with other devices such as smartphones, such as various smart bracelets and smart jewelry for vital sign monitoring.

[0189] In addition, in the embodiments of the present application, the terminal may also be a terminal device in the Internet of Things (IoT) system. The IoT is an important component of the future development of information technology. Its main technical feature is to connect objects to the network through communication technology, thereby realizing an intelligent network that interconnects people and machines and things. The embodiments of the present application do not limit the specific technology and specific device form used by the terminal.

[0190] A radio access network (RAN) device is an access device that a terminal uses to access the mobile communication system wirelessly. It can be a base station NodeB, an evolved NodeB (eNB), a next-generation NodeB (gNB) in a 5G mobile communication system, a transmission point, a base station in a future mobile communication system, an access node in a Wi-Fi system, one or more antenna panels of a base station in a 5G system, or a network node that constitutes a gNB or a transmission point, such as a baseband unit (BBU) or a distributed unit (DU). The embodiments of the present application do not limit the specific technology and specific device form adopted by the radio access network device. In some deployments, the gNB may include a centralized unit (CU) and a DU, each of which implements part of the gNB's functions. For example, the CU is responsible for processing non-real-time protocols and services and implementing the functions of the radio resource control (RRC) and packet data convergence protocol (PDCP) layers. The DU is responsible for processing physical layer protocols and real-time services, implementing the functions of the radio link control (RLC) layer, the media access control (MAC) layer, and the physical (PHY) layer. The gNB may also include an active antenna unit (AAU). The AAU implements some physical layer processing functions, RF processing, and active antenna-related functions. Since RRC layer information will eventually become PHY layer information, or be converted from PHY layer information, in this architecture, high-layer signaling, such as RRC layer signaling, can also be considered to be sent by the DU, or by the DU+AAU. It is understood that the network device can be a device including one or more of a CU node, a DU node, and an AAU node. In addition, the CU can serve as a network device in the access network or as a network device in the core network (CN), and this application does not limit this.

[0191] Wireless access network equipment and terminals can be deployed on land, including indoors or outdoors, handheld or vehicle-mounted; can also be deployed on water; and can also be deployed in the air on aircraft, balloons, and satellites. The embodiments of this application do not limit the application scenarios of wireless access network equipment and terminals.

[0192] The wireless access network device and the terminal, as well as the terminal and the terminal, can communicate through the licensed spectrum (licensed spectrum), or can communicate through the unlicensed spectrum (unlicensed spectrum), or can communicate through the licensed spectrum and the unlicensed spectrum at the same time. The wireless access network device and the terminal, as well as the terminal and the terminal, can communicate through the spectrum below 6 gigahertz (GHz), or can communicate through the spectrum above 6G, or can communicate using the spectrum below 6G and the spectrum above 6G at the same time. The embodiments of the present application do not limit the spectrum resources used between the wireless access network device and the terminal.

[0193] In an embodiment of the present application, a terminal or network device includes a hardware layer, an operating system layer running on the hardware layer, and an application layer running on the operating system layer. The hardware layer includes hardware such as a central processing unit (CPU), a memory management unit (MMU), and memory (also called main memory). The operating system can be any one or more computer operating systems that implement business processing through processes, such as a Linux operating system, a Unix operating system, an Android operating system, an iOS operating system, or a Windows operating system. The application layer includes applications such as browsers, address books, word processing software, and instant messaging software. In addition, the embodiment of the present application does not specifically limit the specific structure of the execution subject of the method provided in the embodiment of the present application. As long as it is possible to communicate according to the method provided in the embodiment of the present application by running a program that records the code of the method provided in the embodiment of the present application, for example, the execution subject of the method provided in the embodiment of the present application can be a terminal device or a network device, or a functional module in a terminal device or a network device that can call a program and execute the program.

[0194] In addition, various aspects or features of the present application can be implemented as methods, devices or products using standard programming and / or engineering techniques. The term "product" as used in this application covers computer programs that can be accessed from any computer-readable device, carrier or medium. For example, computer-readable media may include, but are not limited to: magnetic storage devices (e.g., hard disks, floppy disks or magnetic tapes, etc.), optical disks (e.g., compact discs (CDs), digital versatile discs (DVDs), etc.), smart cards and flash memory devices (e.g., erasable programmable read-only memories (EPROMs), cards, sticks or key drives, etc.). In addition, the various storage media described herein may represent one or more devices and / or other machine-readable media for storing information. The term "machine-readable medium" may include, but is not limited to, wireless channels and various other media capable of storing, containing and / or carrying instructions and / or data.

[0195] During the process of establishing a call connection between the calling terminal and the called terminal, the called terminal will send a success response message (such as 200OK) to the calling side core network device through the called core network device, and after a period of time, send a ringing message (such as 180Ringing) to the calling side core network device through the called core network device.

[0196] The following is described in conjunction with the example in Figure 2. Figure 2 shows an example diagram of part of the process of establishing a call connection between the calling terminal and the called terminal. As shown in Figure 2:

[0197] Step 1: The called terminal sends a 200OK message to the called core network device.

[0198] The 200OK message carries the "local none" field, which indicates that no voice bearer has been established between the called terminal and the called core network device.

[0199] Step 2: The called core network device sends a 200 OK message to the calling core network device.

[0200] Step 3: After receiving the 200OK message, the calling core network device closes the media forwarding port based on the local none in the 200OK message.

[0201] Step 4: The calling core network device sends a 200 OK message to the calling terminal.

[0202] Step 5: The called terminal establishes a voice bearer with the called core network device.

[0203] Step 6: The called terminal sends a 180Ringing message to the called core network device.

[0204] Step 7: The called core network device forwards the 180Ringing message to the calling core network device.

[0205] Step 8: The calling core network device opens the media forwarding port according to the 180Ringing message.

[0206] Step 9: The calling core network device sends a 180Ringing message to the calling terminal.

[0207] In the scenario shown in Figure 2, the called terminal first sends a 200OK message to the calling terminal, followed by a 180Ringing message, via the called and calling core network devices. Normally, the 200OK message arrives at the calling core network device first, followed by the 180Ringing message. In this case, the calling core network device can forward voice packets between the calling and called terminals via the media forwarding port opened by the 180Ringing message, ensuring a continuous call between the calling and called terminals.

[0208] However, in the scenario shown in Figure 2, if the interval between the called terminal sending the 200 OK (with local none) message and the 180 Ringing message is extremely short—for example, less than a certain value (typically 200ms)—during message transmission, the 180 Ringing message may arrive at the calling core network device before the 200 OK (with local none) message, resulting in message out-of-order transmission. This is described below using the example shown in Figure 3.

[0209] Figure 3 shows an example diagram of part of the process when messages are out of order. As shown in Figure 3:

[0210] Step 1: The called terminal sends a 200OK message to the called core network device. The 200OK message carries "local none". For an explanation of "local none", refer to the description in Figure 2.

[0211] The 200OK message is a successful response message.

[0212] Step 2: The called core network device sends a 200 OK (carrying local none) message to the calling core network device.

[0213] Step 3: The called terminal establishes a voice bearer with the called core network device.

[0214] Step 4: The called terminal sends a 180Ringing message to the called core network device.

[0215] The 180Ringing message is a ringing message. The 180Ringing message indicates that the called terminal has started ringing.

[0216] Step 5: The called core network device forwards the 180Ringing message to the calling core network device.

[0217] Step 6: After receiving the 180Ringing message, the calling core network device may open the media forwarding port to forward the media packet.

[0218] Step 7: The calling core network device sends a 180Ringing message to the calling terminal.

[0219] Step 8: The calling core network device closes the media forwarding port based on the received 200 OK message (carrying local none).

[0220] When the time interval between the called terminal sending the 200OK (carrying local none) message and the 180Ringing message is small, the 200OK (carrying local none) message arrives at the calling core network device later than the 180Ringing message, that is, the messages are out of order.

[0221] Because the 200OK (carrying "local none") and 180Ringing messages arrive at the calling-side core network device out of order after being transmitted through the network, the calling-side core network device receives the 180Ringing message first and then the 200OK (carrying "local none"). Upon receiving the 180Ringing message, the calling-side core network device sets the call status to ringing based on the 180Ringing message and opens the media forwarding port. Upon receiving the 200OK message, if the 200OK message carries "local none," the calling-side core network device closes the media forwarding port. After closing the media forwarding port, even if the call between the calling and called terminals is connected, the calling-side core network device will be unable to forward the voice media (or voice packets) transmitted between the calling and called terminals, resulting in silence after the call is connected. This results in a two-way silence, impacting the user experience.

[0222] It should be understood that the processes in Figure 2 or Figure 3 are described by taking part of the processes in the Session Initiation Protocol SIP as an example. In fact, the process of establishing a call connection between the calling terminal and the called terminal may include more processes.

[0223] It should also be understood that the messages or signaling involved in Figure 2 or Figure 3 may be messages or signaling in SIP, and for relevant specific explanations, reference may be made to the description in SIP. The above message description is only a brief introduction.

[0224] In view of this, an embodiment of the present application proposes a method for call connection. After the called terminal receives a switching indication (for example, the switching indication is used to instruct the terminal to switch from NR to LTE), it sends a 200OK (carrying local none) message (corresponding to the first response message below) to the called core network device, without waiting for the TAU to be completed before sending the 200OK (carrying local none) message, so that the time interval between the time the called terminal sends the 200OK (carrying local none) message and the time interval between sending the 180Ringing message is longer, that is: the time interval between the terminal sending the 200OK (carrying local none) message and sending the 180Ringing message during the call process in the embodiment of the present application is greater than the time interval between the called terminal sending the 200OK (carrying local none) message and sending the 180Ringing message in the current technology. This can avoid the message disorder problem caused by the 180Ringing message arriving at the calling core network device earlier than the 200OK (carrying local none) message, so that the calling core network device can smoothly forward the voice packet on the called side, reducing the probability of silent call.

[0225] The following describes a method for call connection according to an embodiment of the present application in conjunction with FIG. 4 to FIG. 9 .

[0226] Refer to Figure 4, which is a schematic flow chart of a call connection according to an embodiment of the present application. As shown in Figure 4, it includes:

[0227] Step 300: The called terminal receives a session invitation from the calling terminal, where the session invitation is used to request to establish a voice call with the called terminal.

[0228] Step 301: The called terminal sends a request response message to the calling terminal. The request response message is a response to the session invitation and is used to indicate that the called terminal has received the session invitation.

[0229] It should be understood that the introduction of steps 300 and 301 is to simply introduce the call scenario between the called terminal and the calling terminal, and the embodiments of the present application are not limited thereto. In fact, the call scenario between the calling terminal and the called terminal may include more other messages or signaling, which will not be expanded in detail here.

[0230] Step 302: The called terminal receives an update message from the called core network device.

[0231] Exemplarily, the update message is an Update message.

[0232] In step 303, when the called terminal falls back from NR to LTE, the called terminal determines whether a handover instruction is received. The handover instruction is used to notify the called terminal to switch from the first communication standard to the second communication standard.

[0233] If the called terminal receives the switching instruction, step 304 is executed; if the called terminal does not receive the switching instruction, the communication mode switching is not executed.

[0234] Step 304: The called terminal switches from the first communication standard to the second communication standard according to the switching instruction.

[0235] Exemplarily, the first communication standard is the 5G standard, and the second communication standard is the LTE standard. The called terminal switches from the 5G standard to the LTE standard, or from the NR standard to the LTE standard, according to the switching instruction.

[0236] Alternatively, illustratively, the switching indication is an EPSFB switching indication.

[0237] Step 305: After receiving the update message and before the tracking area update (TAU) is completed, the called terminal sends a first response message (200 OK message) to the called core network device. The first response message is a response to the update message, indicating that the called terminal has received the update message. The first response message carries a first parameter (for example, the value of the first parameter is local none), indicating that no voice bearer has been established between the called terminal and the called core network device.

[0238] Optionally, as an implementation manner, step 305 includes: the called terminal sends the first response message after receiving the switching indication and switching from the first communication standard to the second communication standard, and before the tracking area update TAU is completed.

[0239] Exemplarily, the called terminal may send a first response message to the calling terminal after receiving a switching indication and switching from the NR standard to the LTE standard, and before the TAU is updated.

[0240] Step 306: After the called terminal sends the first response message, the called terminal sends a ringing message (ie, a 180Ringing message) to the called core network device. The ringing message is used to notify the calling terminal that the called terminal has started ringing.

[0241] Compared to the case where the called terminal waits for the TAU to be completed before sending the first response message, in an embodiment of the present application, the called terminal does not need to wait for the TAU to be completed before sending the first response message. Instead, the called terminal sends the first response message after receiving the switching indication and before the TAU, thereby lengthening the time interval between the time when the called terminal sends the first response message and the time interval between the time when the ringing message is sent. In this way, although no voice bearer is created between the called terminal and the called core network device when the first response message is sent, since the sending time of the first response message is advanced, the time when the first response message arrives at the calling core network device will also be earlier than the ringing message, thereby avoiding the message disorder problem caused when the ringing message arrives earlier than the first response message, and enabling the calling core network device to smoothly forward the voice packet on the called side, thereby reducing the probability of silent calls.

[0242] Optionally, after sending the first response message, the method further includes: the called terminal performing a tracking area update TAU process after sending the first response message; and the called terminal establishing a voice bearer with the called core network device.

[0243] Optionally, the called terminal establishes a voice bearer with the called core network device, including: after receiving a voice bearer establishment message from the called core network device, the called terminal establishes a voice bearer with the called terminal according to the voice bearer establishment message; the called terminal sends a voice bearer establishment completion message to the called core network device, and the voice bearer establishment completion message is used to indicate that the called terminal and the called core network device have established a voice bearer.

[0244] Referring to FIG5 , FIG5 shows a schematic flow diagram of a method for call connection according to an embodiment of the present application. It should be understood that the various messages involved in the steps shown in FIG5 may be existing messages in the SIP protocol or newly defined messages, and this is not specifically limited. As shown in FIG5 , the method includes:

[0245] Step 400-1: The calling terminal sends a session invitation to the calling core network device, where the session invitation is used to request to establish a voice call with the called terminal.

[0246] Step 400-2: The calling core network device sends the session invitation to the called core network device.

[0247] Step 400-3: The called core network device sends the session invitation to the called terminal.

[0248] Step 400-4: The called terminal sends a request response message to the called core network device. The request response is a response to the session invitation, and is used to indicate that the called terminal has received the session invitation message.

[0249] Step 400-5: The called core network device sends the request response message to the calling core network device.

[0250] Step 400-6: The calling core network device sends the request response message to the calling terminal.

[0251] Step 401-1: The calling terminal sends an update message to the calling core network device.

[0252] Step 401-2: The calling core network device sends an update message to the called core network device.

[0253] In step 401-3, the called core network device sends an update message to the called terminal. Correspondingly, the called terminal receives the update message from the called core network device.

[0254] Exemplarily, in the process of establishing a connection between the calling terminal and the called terminal, the called terminal is in the NR communication scenario, and the update message is sent to the called terminal through the following process: the calling terminal sends the update message to the calling core network device; the calling core network device forwards the update message to the called core network device; the called core network device sends the update message to the called terminal through the NR access network device.

[0255] Exemplarily, the update message is an Update message. The Update message is used to initiate an update request. Generally speaking, the Update message is used to initiate a media update.

[0256] In step 402, when the called terminal falls back from NR to LTE, the NR access network device sends a handover instruction to the called terminal. In response, the called terminal receives the handover instruction from the NR access network device, which notifies the called terminal to switch from the first communication standard to the second communication standard. The first communication standard and the second communication standard are different.

[0257] Exemplarily, the switching indication is used to instruct the called terminal to switch from the NR standard to the LTE standard.

[0258] After receiving the switching instruction, the called terminal switches from the first communication standard to the second communication standard according to the switching instruction.

[0259] It should be understood that the description here is only based on the example of switching from the NR standard to the LTE standard, and the embodiments of the present application are not limited to this.

[0260] Before the NR access network device sends a handover instruction to the called terminal, the NR access network device may instruct the called terminal to perform network measurements. Optionally, before step 402, the method further includes: the NR access network device sending a measurement configuration message to the called terminal; and the called terminal sending a measurement result to the NR access network device.

[0261] Exemplarily, the measurement configuration message is used to notify the called terminal to perform LTE measurements. For example, in step 402-1, the called terminal performs measurements on the LTE access network device; in step 402-2, after the measurements are completed, the called terminal may feed back the measurement results (e.g., an LTE measurement report) to the NR access network device.

[0262] Step 403-1: After the called terminal receives the handover indication and before the tracking area update (TAU) is completed, the called terminal sends a first response message to the called core network device. The first response message carries a first parameter indicating that no voice bearer has been established between the called terminal and the called core network device.

[0263] The first response message is used by the called terminal to confirm receipt of the update message. Alternatively, the first response message indicates that the called terminal has received the update message. Furthermore, the called terminal may include in the first response message a parameter indicating whether a voice bearer has been established. The voice bearer is a voice bearer between the called terminal and the called core network device.

[0264] Exemplarily, the first response message is a 200 OK message.The value of the first parameter is local none.

[0265] The first response message can pass through the called core network device and the calling core network device, ultimately reaching the calling terminal. For example, in a specific implementation, the called core network device sends the first response message, including: step 403-2, the called core network device sends the first response message to the calling core network device; step 403-3, the calling core network device closes the media forwarding port based on the first response message; and step 403-4, the calling core network device sends the first response message to the calling terminal.

[0266] For the calling core network device, after receiving the first response message, the media forwarding port may be closed according to the first parameter in the first response message.

[0267] Step 404-1: The TAU update process is performed between the called terminal and the called core network device.

[0268] Step 404-2: After the TAU update is completed, the called terminal sends a handover confirmation to the LTE access network device.

[0269] Step 405-1: The called core network device sends a voice bearer establishment message to the called terminal.

[0270] After receiving the voice bearer establishment message, the called terminal establishes a voice bearer with the called core network device. After the voice bearer is established between the called terminal and the called core network device, the called terminal sends a voice bearer establishment success message to the called core network device.

[0271] For example, the voice bearer establishment message includes a QoS class identifier (QCI) of 1. It is understood that different QCI values ​​may correspond to different bearers. When QCI = 1, it indicates that a voice service bearer is being established. In other words, QCI = 1 corresponds to a dedicated voice bearer.

[0272] Step 405-2: The called terminal sends a voice bearer establishment completion message to the called core network device. The voice bearer establishment completion message indicates that the voice bearer between the called terminal and the called core network device has been established.

[0273] Step 406-1: The called terminal sends a ringing message to the called core network device. The ringing message is used to notify the calling terminal that the called terminal has started ringing.

[0274] Exemplarily, the ringing message is a 180Ringing message.

[0275] The ringing message can reach the calling terminal via the called core network device and the calling core network device. For example, in step 406-2, the called core network device sends the ringing message to the calling core network device. In step 407-1, the calling core network device opens the media forwarding port based on the ringing message. In step 407-2, the calling core network device sends the ringing message to the calling terminal. Upon receiving the ringing message, the calling terminal is informed that the called terminal has started ringing.

[0276] For example, the calling core network device sets the calling side's call state to ringing state according to the ringing message and opens the media forwarding port. After the media forwarding port is opened, the calling core network device can subsequently forward the called side's media data (including voice packets) to the calling terminal.

[0277] Optionally, after step 407, the method further includes:

[0278] Step 408-1: The called terminal sends a session invitation response message to the called core network device. The session invitation response message is used to respond to the session invitation message.

[0279] Step 408-2: The called core network device sends the session invitation response message to the calling core network device.

[0280] Step 408-3: The calling core network device sends the session invitation response message to the calling terminal.

[0281] The session invitation message is used to invite a user to join a session. The session invitation message is sent by the calling terminal, passes through the calling core network device and the called core network device, and finally reaches the called terminal.

[0282] For example, the session invitation message is an Invite message, and the session invitation response message is a 200 OK (Invite) message. The 200 OK (Invite) message is a message sent by the called terminal after the user of the called terminal answers the call.

[0283] Optionally, after the calling core network device receives the session invitation response message, it forwards the voice packet of the called side to the calling side according to the session invitation response message, thereby ensuring that the call between the calling terminal and the called terminal is normal after the call is connected, and reducing the probability of silent two-way calls.

[0284] In an embodiment of the present application, after receiving an update message from the called core network device, the called terminal sends a first response message to the called core network device without waiting for the TAU to complete. Compared to the case where the called terminal waits for the TAU to complete before sending the first response message, the called terminal does not need to wait for the TAU to complete before sending the first response message. This increases the time interval between the called terminal sending the first response message and sending the ringing message. Specifically, the time interval between the called terminal sending the first response message and sending the ringing message in the embodiment of the present application is greater than the time interval between the called terminal sending the first response message and sending the ringing message in the prior art. Thus, although a voice bearer is not established between the called terminal and the called core network device when the first response message is sent, the first response message arrives at the calling core network device earlier than the ringing message due to the earlier sending time of the first response message. This avoids the message out-of-order issue that occurs when the ringing message arrives before the first response message, allowing the calling core network device to smoothly forward the voice packets from the called party, reducing the probability of silent calls.

[0285] The called terminal sends the first response message before the tracking area update is completed. Optionally, after the called terminal sends the first response message, the step 404-1, in which the called terminal and the called core network device perform a TAU update process, includes:

[0286] Sending a first request message, where the first request message is used to request updating of a tracking area;

[0287] receiving an acceptance message from the called core network device, where the acceptance message is used to respond to the first request message;

[0288] A tracking area update completion message is sent to the called core network device, where the tracking area update completion message indicates that the tracking area update process is completed.

[0289] Exemplarily, the first request message is a TAU request, the acceptance message of the called core network device is a TAU accept message, and the tracking area update completion message is a TAU completion.

[0290] That is to say, through the above-mentioned TAU update related steps, the called terminal can initiate a TAU update process after sending the first response message to complete the TAU update process.

[0291] It should be noted that the method in FIG5 illustrates only some of the steps for establishing a call connection between a calling terminal and a called terminal. The embodiments of the present application are not limited thereto. In fact, the method for establishing a call connection between a calling terminal and a called terminal may also include other steps. This will be described below with reference to the example in FIG6.

[0292] Figure 6 shows an example interaction diagram of establishing a call connection between a calling terminal and a called terminal according to an embodiment of the present application. It should be understood that the examples of messages or signaling involved in Figure 6 are described using the examples of messages or signaling involved in SIP, and the embodiments of the present application are not limited thereto. As shown in Figure 6, the interaction process includes the following steps:

[0293] Step 501-1, the calling terminal sends a session invitation to the calling core network device; Step 501-2, the calling core network device sends a session invitation to the called core network device; Step 501-3, the called core network device sends a session invitation to the called terminal.

[0294] The session invitation is used to initiate a session request. For example, the session invitation is used to invite the called terminal to join a session created by the calling terminal, or to request to establish a voice call with the called terminal.

[0295] Illustratively, the session invitation is an Invite message.

[0296] Optionally, the session invitation includes session description information, where the session description information is used to indicate media types and parameters that the calling terminal can receive.

[0297] Step 502-1, the called terminal sends a request response message to the called core network device; Step 502-2, the called core network device forwards the request response message to the calling core network device; Step 502-3, the calling core network device forwards the request response message to the calling terminal.

[0298] The request response message is used to indicate that the called terminal has received the session invitation message and is processing the message. For example, the request response message is a 100Trying message.

[0299] Step 503a: The calling core network device sends a voice bearer establishment message on the calling side to the calling terminal.

[0300] Optionally, the voice bearer establishment message includes a bearer with QCI = 1. The bearer with QCI = 1 represents the establishment of a dedicated bearer for voice service.

[0301] Exemplarily, the voice bearer establishment message on the calling side is an Activate Dedicated EPS Bearer Context Request message. This Activate Dedicated EPS Bearer Context Request message is sent by the calling core network device to the calling terminal to request activation of a dedicated EPS bearer context. The dedicated EPS bearer has the same PDN address and APN as the activated EPS bearer context.

[0302] Step 503b: The calling terminal sends a voice bearer setup completion message to the calling core network device. The voice bearer setup completion message indicates that the calling terminal and the calling core network device have established a voice bearer.

[0303] Exemplarily, the voice bearer establishment completion message is an Activate Dedicated EPS Bearer Context Accept message. The Activate Dedicated EPS Bearer Context Accept message is sent by the calling terminal to the calling core network device to confirm activation of the dedicated EPS bearer context.

[0304] The above steps 503a and 503b are used to establish a voice bearer between the calling terminal and the calling core network device.

[0305] Step 504-1: The called terminal sends a message related to the session progress to the called core network device.

[0306] In step 504-2, the called core network device forwards the message related to the session progress to the calling core network device.

[0307] Step 504-3: The calling core network device forwards the message related to the session progress to the calling terminal.

[0308] For example, the message related to the session progress is a 183 message. The 183 message can be used to establish an early media service, such as a user-customized ringback tone or ring tone.

[0309] The calling terminal sends a temporary response message to the called terminal.

[0310] Step 505-1: The calling terminal sends a temporary response message to the calling core network device.

[0311] Step 505-2: The calling core network device sends a temporary response message to the called core network device.

[0312] Step 505-3: The called core network device sends a provisional response message to the called terminal. The provisional response message is used to confirm that the session progress-related message in step 504 has been received.

[0313] For example, the provisional response message is a provisional response acknowledgement (PRACK) message, which is used to acknowledge the 183 message when the session is established and to perform a second SDP provision to negotiate media resources.

[0314] The called terminal sends a temporary answer success response message to the calling terminal.

[0315] Step 506-1: The called terminal sends a temporary answer success response message to the called core network device.

[0316] Step 506-2: The called core network device forwards the temporary answer success response message to the calling core network device.

[0317] Step 506-3: The calling core network device forwards the temporary answer success response message to the calling terminal.

[0318] The provisional answer success response message is used to indicate that the called terminal has successfully received the provisional response message.

[0319] Exemplarily, the provisional acknowledgement success response message is a 200 OK (PRACK) message.

[0320] Step 507-1: The calling terminal sends an update message to the calling core network device.

[0321] Step 507-2: The calling core network device forwards the update message to the called core network device.

[0322] Step 507-3: The called core network device forwards the update message to the called terminal.

[0323] The update message is used to initiate an update request, or in other words, to update the media.

[0324] Exemplarily, the update message is an Update message.

[0325] Step 508a: The called core network device sends the LTE measurement configuration to the called terminal.

[0326] Optionally, the LTE measurement configuration may be carried in an RRC reconfiguration message (RRCConnectionReconfiguration). The RRC reconfiguration message is used to allocate radio resources.

[0327] Optionally, the RRC reconfiguration message may be sent by the called core network device to the called terminal via the access network device on the called side.

[0328] Step 508b: The called terminal sends an LTE measurement report (MeasurementReport) to the called core network device.

[0329] Exemplarily, the called terminal may report the LTE measurement report to the called core network device via the access network device on the called side.

[0330] Step 509: The called core network device sends a handover instruction to the called terminal.

[0331] Optionally, the handover instruction may be sent to the called terminal via an RRC release message. The RRC release message is used to instruct the called terminal to release radio resources.

[0332] Alternatively, the handover indication may be sent to the called terminal via a handover instruction (MobilityFromNRCommand). The handover instruction is used to notify the called terminal to switch from the NR network to the LTE network.

[0333] Step 510: The called terminal sends a first response message to the calling terminal. The first response message corresponds to the first response message in FIG.

[0334] Specifically, step 510 includes: 510-1, the called terminal sends a first response message to the called core network device, and the first response message carries local none; 510-2, the called core network device forwards the first response message to the calling core network device; 510-3, the calling core network device closes the media forwarding port based on local none; 510-4, the calling core network device forwards the first response message to the calling terminal.

[0335] Exemplarily, the first response message is a 200OK(Update) message. Because a voice bearer has not yet been established between the called terminal and the called core network device, the 200OK(Update) message carries the "local none" field. This field indicates that a voice bearer has not yet been established between the called terminal and the called core network device. Upon receiving the 200OK(Update) message, the calling core network device closes the media forwarding port based on the "local none" condition.

[0336] In step 511a, the called terminal sends a tracking area update (TAU) request message to the called core network device. The TAU request message is used by the called terminal to update the real tracking area registration to the network.

[0337] Exemplarily, the TAU request message is Tracking Area Update Request.

[0338] Step 511b: The called core network device sends a TAU accept message to the called terminal. The TAU accept message is used to respond to the TAU request message.

[0339] Exemplarily, the TAU accept message is Tracking Area Update Accept. Tracking Area Update Accept is a message sent by the network side to the terminal, used to provide EPS mobility management related data in order to respond to the Tracking Area Update Request message.

[0340] Step 511c: The called terminal sends a TAU completion message to the called core network device. The TAU completion message is used to indicate that the tracking area update process has been completed.

[0341] For example, the TAU completion message is Tracking Area Update Complete. If the GUTI has been changed or a new TMSI has been allocated, the called terminal sends this message to the network in response to the Tracking Area Update Accept message.

[0342] Step 512a: The called core network device sends a voice bearer establishment message on the called side to the called terminal.

[0343] Optionally, the voice bearer establishment message includes a bearer with QCI = 1. The bearer with QCI = 1 represents the establishment of a dedicated bearer for voice service.

[0344] For example, similar to step 503a, the voice bearer establishment message on the called side may also be Activate Dedicated EPS Bearer Context Request. For the explanation of the message, please refer to the above text and will not be repeated here.

[0345] Step 512b: The called terminal sends a voice bearer establishment completion message on the called side to the called core network device.

[0346] For example, similar to step 503b, the voice bearer establishment completion message on the called side may also be Activate Dedicated EPS Bearer Context Accept. For the explanation of the message, please refer to the above text and will not be repeated here.

[0347] In step 513-1, the called terminal sends a ringing message to the called core network device. In step 513-2, the called core network device sends a ringing message to the calling core network device.

[0348] Exemplarily, the ringing message is a 180Ringing message.

[0349] Step 514: After receiving the ringing message, the calling core network device opens the media forwarding port.

[0350] Step 515: The calling core network device sends a ringing message to the calling terminal.

[0351] In step 516-1, the called terminal sends a session invitation response message to the called core network device. In step 516-2, the called core network device sends a session invitation response message to the calling core network device. In step 516-3, the calling core network device sends a session invitation response message to the calling terminal. Exemplarily, the session invitation response message is a 200 OK (Invite) message.

[0352] In step 517-1, the calling terminal sends a final response message to the calling core network device; in step 517-2, the calling core network device sends a final response message to the called core network device; in step 517-3, the called core network device sends a final response message to the called terminal.

[0353] Exemplarily, the final response message is an ACK (Invite) message.

[0354] In step 518-1, the calling terminal sends a session-end message to the calling core network device. In step 518-2, the calling core network device sends a session-end message to the called core network device. In step 518-3, the called core network device sends a session-end message to the called terminal. The session-end message is used to terminate the current session.

[0355] Exemplarily, the end-session message is a BYE message.

[0356] In step 519-1, the called terminal sends a session end response message to the called core network device. In step 519-2, the called core network device sends a session end response message to the calling core network device. In step 519-3, the calling core network device sends a session end response message to the calling terminal. The session end response message is used to respond to the session end message.

[0357] Exemplarily, the end-session response message is an ACK(BYE) message.

[0358] In the process shown in Figure 6, the sending time of the 200OK (Update) message is advanced to before the TAU update process, so the 200OK (Update) message arrives at the calling core network device earlier than the 180Ringing message. This enables the calling core network device to forward the voice packet, reducing the probability of silent call.

[0359] It should be noted that the steps shown in FIG6 are merely examples of a call connection establishment process, and the embodiments of the present application are not limited thereto.

[0360] This embodiment of the present application also provides another method for connecting a call. In this method, a timer is set on the called terminal. If the voice bearer is established within the timer, the called terminal can send a response message with a parameter indicating that the voice bearer has been established, thereby preventing the calling core network from not forwarding voice packets. This other method for connecting a call according to this embodiment of the present application will be described below with reference to Figures 7 to 9.

[0361] Refer to Figure 7, which is a schematic flow chart of another embodiment of the present application for call connection. As shown in Figure 7, it includes:

[0362] Step 900: The called terminal receives a session invitation from the calling terminal, where the session invitation is used to request to establish a voice call with the called terminal.

[0363] Step 901: The called terminal sends a request response message to the calling terminal. The request response message is a response to the session invitation and is used to indicate that the called terminal has received the session invitation.

[0364] It should be understood that the introduction of steps 900 and 901 is to simply introduce the call scenario between the called terminal and the calling terminal, and the embodiments of the present application are not limited thereto. In fact, the call scenario between the calling terminal and the called terminal may include more other messages or signaling, which will not be expanded in detail here.

[0365] Step 902: The called terminal receives an update message from the called core network device.

[0366] Exemplarily, the update message is an Update message.

[0367] Step 903: After receiving the update message, the called terminal starts a first timer.

[0368] Step 904: The called terminal receives a switching instruction within the first timer, where the switching instruction is used to notify the called terminal to switch from the first communication standard to the second communication standard.

[0369] Step 905: the called terminal switches from the first communication standard to the second communication standard according to the switching instruction;

[0370] Step 906: The called terminal determines whether a voice bearer establishment message is received from the called core network device within the first timer.

[0371] If a voice bearer establishment message is received from the called core network device within the first timer, steps 907 and 908 are executed; if no voice bearer establishment message is received from the called core network device within the first timer, steps 909 to 910 are executed.

[0372] Optionally, within the first timer, after receiving the voice bearer establishment message from the called core network device, the called terminal establishes a voice bearer with the called terminal according to the voice bearer establishment message; the called terminal sends a voice bearer establishment completion message to the called core network device, and the voice bearer establishment completion message is used to indicate that the called terminal and the called core network device have established a voice bearer.

[0373] Step 907, within the first timer, the called terminal receives a voice bearer establishment message from the called core network device after switching from the first communication standard to the second communication standard, and after receiving the voice bearer establishment message, a voice bearer is established between the called terminal and the called core network device. The called terminal sends a second response message (200OK message) to the called core network device, and the second response message is a response to the update message. The second response message is used to indicate that the called terminal has received the update message. The second response message carries a second parameter (for example, the value of the second parameter is local sendrecv), and the second parameter indicates that the called terminal and the called core network device have established a voice bearer.

[0374] Step 908: After the called terminal sends the second response message, the called terminal sends a ringing message to the called core network device. The ringing message is used to notify the calling terminal that the called terminal has started ringing.

[0375] Step 909: If the called terminal has not received the voice bearer establishment message from the called core network device until the first timer expires, the called terminal sends a third response message (200OK message) to the called core network device. The third response message is a response to the update message. The third response message is used to indicate that the called terminal has received the update message. The third response message carries a first parameter (for example, the value of the first parameter is local none). The first parameter indicates that the called terminal and the called core network device have not established a voice bearer.

[0376] Step 910: After sending the third response message, a ringing message is sent to the called core network device. The ringing message is used to notify the calling terminal that the called terminal has started ringing.

[0377] Optionally, after sending the third response message to the called core network device and before sending the ringing message to the called core network device, the method further includes:

[0378] Receive a voice bearer establishment message from the called core network device;

[0379] Send a voice bearer establishment completion message to the called core network device.

[0380] That is, the called terminal waits for the voice bearer establishment message from the called core network device. After the voice bearer establishment between the called terminal and the called core network device is completed, the called terminal sends a ringing message to the called core network device.

[0381] In an embodiment of the present application, after receiving an update message from the called core network device, the called terminal starts a first timer and then detects whether a voice bearer establishment message is received from the called core network device within the first timer. If a voice bearer establishment message is received from the called core network device within the first timer, the called terminal sends a second response message (such as a 200OK message) to the called core network device, and carries a second parameter in the second response message, and the second parameter indicates that a voice bearer has been established between the called terminal and the called core network device. Compared to the situation where the second response message is sent without waiting for the voice bearer to be established, the embodiment of the present application sets a timer to wait for the voice bearer to be established. If the voice bearer is established during the timer operation, the calling core network device can smoothly forward the voice packet, thereby reducing the probability of silent calls.

[0382] Referring to FIG8 , FIG8 shows a schematic flow diagram of a method for call connection according to an embodiment of the present application. It should be understood that the various messages involved in the steps shown in FIG8 may be existing messages in the SIP protocol or newly defined messages, and this is not specifically limited. It should also be understood that the explanation of some of the messages involved in FIG8 can refer to the explanation in FIG5 above, and for the sake of brevity, it will not be repeated here. As shown in FIG8 , the method includes:

[0383] Step 600-1: The calling terminal sends a session invitation to the calling core network device, where the session invitation is used to request to establish a voice call with the called terminal.

[0384] Step 600-2: The calling core network device sends the session invitation to the called core network device.

[0385] Step 600-3: The called core network device sends the session invitation to the called terminal.

[0386] Step 600-4: The called terminal sends a request response message to the called core network device. The request response is a response to the session invitation, and is used to indicate that the called terminal has received the session invitation message.

[0387] Step 600-5: The called core network device sends the request response message to the calling core network device.

[0388] Step 600-6: The calling core network device sends the request response message to the calling terminal.

[0389] Step 601-1: The calling terminal sends an update message to the calling core network device.

[0390] Step 601-2: The calling core network device sends an update message to the called core network device.

[0391] In step 601-3, the called core network device sends an update message to the called terminal. Correspondingly, the called terminal receives the update message from the called core network device.

[0392] Step 602: After receiving the update message, the called terminal starts a first timer.

[0393] Optionally, the duration of the first timer is greater than a first time threshold and less than a second time threshold, and the second time threshold is related to a timer on the called core network side (eg, a TQos timer).

[0394] The embodiment of the present application does not specifically limit the value of the first time threshold, and can be set based on actual needs. For example, the first time threshold can be 1 second, or 2 seconds.

[0395] Optionally, the upper limit of the first timer is related to the timer of the called core network device. Alternatively, the second time threshold may be determined based on the timer of the called core network device. Exemplarily, the duration of the first timer is less than the TQos timer of the called core network device. The TQos timer of the called core network device can be understood as the duration constrained by the called core network device for establishing a voice bearer.

[0396] For example, if the TQos timer of the called core network device is 6 seconds (corresponding to the second time threshold), the duration of the first timer may be greater than 1 second and less than 6 seconds.

[0397] The called terminal may detect, within the first timer, whether a voice bearer establishment message is received from the called core network device.

[0398] Optionally, as an implementation manner, the method further includes:

[0399] Step 603a: within the first timer, the called terminal receives a voice bearer establishment message;

[0400] Step 603b: Within the first timer, the called terminal sends a voice bearer establishment completion message to the called core network device.

[0401] After sending the voice bearer establishment completion message to the called core network device, the called terminal executes step 604 - 1 .

[0402] Step 604-1, in response to the called terminal receiving a voice bearer establishment message from the called core network device within the first timer, the called terminal sends a second response message to the called core network device, and the second response message carries a second parameter, which indicates that the called terminal and the core network have established a voice bearer.

[0403] The second response message is used by the called terminal to confirm that it has received the update message. In other words, the second response message is used to indicate that the called terminal has received the update message. In addition, the called terminal may carry a parameter (such as a second parameter) in the second response message that indicates that the voice bearer has been established.

[0404] Exemplarily, the second response message is a 200 OK (Update) message. The value of the second parameter is local sendrecv. Local sendrecv indicates that a voice bearer has been established between the called terminal and the called core network device.

[0405] The second response message can pass through the called core network device and the calling core network device, ultimately reaching the calling terminal. For example, in a specific implementation, the called core network device sends the second response message, including: step 604-2, where the called core network device sends the second response message to the calling core network device; step 604-3, where the calling core network device opens a media forwarding port based on the second response message; and step 604-4, where the calling core network device sends the second response message to the calling terminal.

[0406] For the calling core network device, after receiving the second response message, the media forwarding port may be opened according to the second parameter in the second response message.

[0407] That is, if the voice bearer is established within the first timer, the called terminal may send a second response message to the called core network, and carry the second parameter in the second response message to inform the called core network that the voice bearer has been established.

[0408] It should be noted that the purpose of introducing the first timer is to prevent the called terminal from waiting indefinitely. If the first timer expires and the voice bearer establishment message sent by the called core network device has not been received, the called terminal will no longer wait and send a third response message to the called core network device.

[0409] Or, optionally, as another implementation, if the called terminal does not receive the voice bearer establishment message within the first timer, the called terminal executes step 605 - 1 , step 606 - 2 , and step 607 - 1 .

[0410] Optionally, the method also includes: step 605-1, in response to the called terminal not receiving a voice bearer establishment message from the called core network device within the first timer, the called terminal sends a third response message to the called core network device, and the third response message carries a first parameter, and the first parameter indicates that the called terminal and the called core network device have not established a voice bearer.

[0411] Similarly, the third response message is used by the called terminal to confirm that it has received the update message. In other words, the third response message is used to indicate that the called terminal has received the update message. In addition, the called terminal may carry a parameter in the third response message to indicate that the voice bearer has not been established.

[0412] Exemplarily, the third response message is a 200 OK message. The value of the first parameter is local none, which indicates that no voice bearer is established between the called terminal and the called core network device.

[0413] The third response message can pass through the called core network device and the calling core network device, ultimately reaching the calling terminal. For example, in a specific implementation, the called core network device sends the third response message, including: step 605-2, where the called core network device sends the third response message to the calling core network device; step 605-3, where the calling core network device closes the media forwarding port based on the third response message; and step 605-4, where the calling core network device sends the third response message to the calling terminal.

[0414] For the calling core network device, after receiving the third response message, the media forwarding port may be closed according to the first parameter in the third response message.

[0415] Step 607-1: The called terminal sends a ringing message to the called core network device. The ringing message is used to notify the calling terminal that the called terminal has started ringing.

[0416] For the relevant description of the ringing message, please refer to the description in Figure 5 and will not be repeated here.

[0417] Step 607-2: The called core network device sends a ringing message to the calling core network device.

[0418] Step 607-3: The calling core network device opens the media forwarding port according to the ringing message.

[0419] Step 607-4: The calling core network device sends a ringing message to the calling terminal.

[0420] In this implementation, before step 607-1, the method further includes:

[0421] 606-1, the called core network device sends a voice bearer establishment message to the called terminal;

[0422] 606-2, the called terminal sends a voice bearer establishment completion message to the called core network device.

[0423] After the voice bearer between the called terminal and the called core network device is established, step 607-1 can be executed. In other words, before the called terminal sends a ringing message, it needs to wait for the voice bearer between the called terminal and the called core network device to be established.

[0424] For example, if the called terminal does not receive a voice bearer establishment message from the called core network device within the first timer, it will then send a 200OK message to the called core network device after the first timer expires. Furthermore, the called terminal must wait for the voice bearer to be established before sending a 180Ringing message to the called core network device. This increases the time interval between the 200OK and 180Ringing messages, reducing call out-of-order and call silence issues caused by a short time interval, and improving the user experience.

[0425] In an embodiment of the present application, after receiving an update message from the called core network device, the called terminal starts a first timer and then detects whether a voice bearer establishment message is received from the called core network device within the first timer. If the voice bearer establishment message is received from the called core network device within the first timer, the called terminal sends a second response message (e.g., a 200OK message) to the called core network device, and the second response message carries a second parameter, indicating that a voice bearer has been established between the called terminal and the called core network device. Compared with the situation where the called terminal sends a 200OK (carrying local none) message without waiting for the voice bearer to be established, the embodiment of the present application sets a timer to wait for the voice bearer to be established, and then the called terminal can send a 200OK message carrying local sendrecv, which can reduce the number of times the called terminal sends a 200OK message carrying local none (or it can be understood that the probability of the called terminal sending a 200OK message carrying local none) , that is, it can avoid the situation where the calling and called parties are silent in the call due to the calling core network device closing the media forwarding port due to receiving a 200OK message carrying local none after receiving a 180Ringing message. In this way, even if the interval between the sending of the 200OK message carrying local sendrecv sent by the called terminal and the sending of the 180Ringing message sent by the called terminal is very short, even if the two messages are received out of order on the calling core network device side, it will not cause the calling core network device to close the media forwarding port, so that the calling core network device can smoothly forward voice packets, reducing the probability of silent calls.

[0426] It should be noted that the method in FIG8 illustrates only some of the steps for establishing a call connection between a calling terminal and a called terminal. The embodiments of the present application are not limited thereto. In fact, the method for establishing a call connection between a calling terminal and a called terminal may also include other steps. This will be described below with reference to the example in FIG9.

[0427] Figure 9 illustrates an example interaction diagram for establishing a call connection between a calling terminal and a called terminal according to an embodiment of the present application. It should be understood that the examples of messages and signaling in Figure 9 are based on SIP messages and signaling, and the present application is not limited thereto. It should also be understood that some of the messages in Figure 9 have similar functions to those in Figure 6 , and for related explanations, reference can be made to the description in Figure 6 . For the sake of brevity, the explanations and related descriptions of some messages will be omitted when describing the process in Figure 9 .

[0428] The difference between Figure 9 and Figure 6 is that in the process of Figure 9, the called terminal starts a timer after receiving the update message, and then determines the timing of sending the 200OK message based on whether a voice bearer is established with the called core network device within the timer. The following is described in conjunction with Figure 9. As shown in Figure 9, the interaction process includes the following steps:

[0429] Step 701-1, the calling terminal sends a session invitation message to the calling core network device; Step 701-2, the calling core network device sends a session invitation message to the called core network device; Step 701-3, the called core network device sends a session invitation message to the called terminal.

[0430] For explanation or related description of the session invitation message, reference may be made to the explanation of step 501. Exemplarily, the session invitation message is an Invite message.

[0431] In step 702-1, the called terminal sends a request response message to the called core network device; in step 702-2, the called core network device forwards the request response message to the calling core network device; in step 702-3, the calling core network device forwards the request response message to the calling terminal.

[0432] Exemplarily, the request response message is a 100Trying message.

[0433] Step 703a: The calling core network device sends a voice bearer establishment message on the calling side to the calling terminal.

[0434] For explanation or related description of the voice bearer establishment message on the calling side, reference may be made to the explanation of step 503a.

[0435] Step 703b: The calling terminal sends a voice bearer establishment completion message on the calling side to the calling core network device.

[0436] For explanation or related description of the voice bearer establishment completion message on the calling side, please refer to the explanation of step 503b. The above steps 703a and 703b are used to establish a voice bearer between the calling terminal and the calling core network device.

[0437] In step 704-1, the called terminal sends a session progress-related message to the called core network device. In step 704-2, the called core network device forwards the session progress-related message to the calling core network device. In step 704-3, the calling core network device forwards the session progress-related message to the calling terminal. For example, the session progress-related message is a 183 message.

[0438] In step 705-1, the calling terminal sends a temporary response message to the calling core network device, wherein the temporary response message is used to confirm that the message related to the session progress in step 704 has been received.

[0439] Step 705-2: The calling core network device sends a temporary response message to the called core network device.

[0440] Step 705-3: The called core network device sends a temporary response message to the called terminal. Exemplarily, the temporary response message is a PRACK message.

[0441] Step 706-1: The called terminal sends a provisional response success message to the called core network device. Exemplarily, the provisional response success message is a 200 OK (PRACK) message.

[0442] Step 706-2: The called core network device sends a temporary response success message to the calling core network device.

[0443] Step 706-3: The calling core network device sends a temporary response success message to the calling terminal.

[0444] Step 707-1: The calling terminal sends an update message to the calling core network device. Exemplarily, the update message is an Update message.

[0445] Step 707 - 2 : The calling core network device sends an update message to the called core network device.

[0446] Step 707-3: The called core network device sends an update message to the called terminal.

[0447] Step 707-4: After receiving the update message, the called terminal starts the first timer.

[0448] Optionally, the duration of the first timer is smaller than the duration of the QoS timer on the called network side.

[0449] Exemplarily, the duration of the first timer is greater than 1 second and less than 6 seconds.

[0450] Step 708: The called core network device sends the LTE measurement configuration to the called terminal.

[0451] Optionally, the LTE measurement configuration may be carried in an RRC reconfiguration message (RRCConnectionReconfiguration). The RRC reconfiguration message is used to allocate radio resources.

[0452] Optionally, the RRC reconfiguration message may be sent by the called core network device to the called terminal via the access network device on the called side.

[0453] Step 709: The called terminal sends an LTE measurement report (MeasurementReport) to the called core network device.

[0454] Exemplarily, the called terminal may report the LTE measurement report to the called core network device via the access network device on the called side.

[0455] Step 710: The called core network device sends a handover instruction to the called terminal.

[0456] Optionally, the handover instruction may be sent to the called terminal via an RRC release message. The RRC release message is used to instruct the called terminal to release radio resources.

[0457] Alternatively, the handover indication may be sent to the called terminal via a handover instruction (MobilityFromNRCommand). The handover instruction is used to notify the called terminal to switch from the NR network to the LTE network.

[0458] Step 711a: The called terminal sends a TAU request message to the called core network device. The TAU request message is used by the called terminal to update the real tracking area registration to the network.

[0459] Exemplarily, the TAU request message is Tracking Area Update Request.

[0460] Step 711b: The called core network device sends a TAU accept message to the called terminal. The TAU accept message is used to respond to the TAU request message.

[0461] Exemplarily, the TAU accept message is Tracking Area Update Accept. Tracking Area Update Accept is a message sent by the network side to the terminal, used to provide EPS mobility management related data in order to respond to the Tracking Area Update Request message.

[0462] Step 711c: The called terminal sends a TAU completion message to the called core network device. The TAU completion message is used to indicate that the tracking area update process has been completed.

[0463] For example, the TAU completion message is Tracking Area Update Complete. If the GUTI has been changed or a new TMSI has been allocated, the called terminal sends this message to the network in response to the Tracking Area Update Accept message.

[0464] Step 712a: While the first timer is running, the called core network device sends a voice bearer establishment message on the called side to the called terminal.

[0465] Optionally, the voice bearer establishment message includes a bearer with QCI = 1. The bearer with QCI = 1 represents the establishment of a dedicated bearer for voice service.

[0466] For example, similar to step 703a, the voice bearer establishment message on the called side may also be Activate Dedicated EPS Bearer Context Request. For the explanation of the message, please refer to the above text and will not be repeated here.

[0467] Step 712b: While the first timer is running, the called terminal sends a voice bearer establishment completion message on the called side to the called core network device.

[0468] For example, similar to step 703b, the voice bearer establishment completion message on the called side may also be Activate Dedicated EPS Bearer Context Accept. For the explanation of the message, please refer to the above text and will not be repeated here.

[0469] As an implementation method, during the first timer running time, the called terminal and the called core network device have established a voice bearer. For example, if the above steps 712a and 712b occur during the first timer running time, then step 713 can be executed.

[0470] In step 713-1, assuming that steps 712a and 712b occur while the first timer is running, the called terminal sends a second response message (200OK(Update) message) to the called core network device. The second response message carries a second parameter (e.g., the value of the second parameter is local sendrecv). The second parameter indicates that a voice bearer has been established between the called terminal and the called core network device.

[0471] Step 713 - 2 : The called core network device forwards the second response message to the calling core network device.

[0472] Step 713 - 3 : After receiving the second response message, the calling core network device opens the media forwarding port.

[0473] Step 713 - 4 : The calling core network device forwards the second response message to the calling terminal.

[0474] Exemplarily, the second response message is a 200OK(Update) message. Because a voice bearer has already been established between the called terminal and the called core network device, the 200OK(Update) message carries the local sendrecv message. The local sendrecv message indicates that a voice bearer has been established between the called terminal and the called core network device. Upon receiving the 200OK(Update) message, the calling core network device opens a media forwarding port based on the local sendrecv message.

[0475] The called terminal sends a ringing message to the calling core network device via the called core network device, specifically including: step 715-1, the called terminal sends a ringing message to the called core network device; step 715-2, the called core network device sends a ringing message to the calling core network device; step 715-3, after receiving the ringing message, the calling core network device opens a media forwarding port according to the ringing message; step 715-4, the calling core network device sends a ringing message to the calling terminal. Exemplarily, the ringing message is a 180Ringing message.

[0476] The called terminal sends an invitation success response message to the calling terminal, specifically including: step 716-1, the called terminal sends an invitation success response message to the called core network device; step 716-2, the called core network device sends an invitation success response message to the calling core network device; step 716-3, the calling core network device sends an invitation success response message to the calling terminal.

[0477] Exemplarily, the invitation success response message is a 200 OK (Invite) message.

[0478] The calling terminal sends a final response message to the called terminal, specifically including: step 717-1, the called terminal sends a final response message to the called core network device; step 717-2, the called core network device sends a final response message to the calling core network device; step 717-3, the calling core network device sends a final response message to the calling terminal.

[0479] Exemplarily, the final response message is an ACK (Invite) message.

[0480] The calling terminal sends a session-end message to the called terminal, specifically including: step 718-1, the called terminal sends a session-end message to the called core network device; step 718-2, the called core network device sends a session-end message to the calling core network device; step 718-3, the calling core network device sends a session-end message to the calling terminal. The session-end message is used to terminate the current session.

[0481] Exemplarily, the end-session message is a BYE message.

[0482] The called terminal sends a session end response message to the calling terminal, specifically including: step 719-1, the called terminal sends a session end response message to the called core network device; step 719-2, the called core network device sends a session end response message to the calling core network device; step 719-3, the calling core network device sends a session end response message to the calling terminal. The session end response message is used to respond to the session end message.

[0483] Exemplarily, the end-session response message is an ACK(BYE) message.

[0484] In the process shown in Figure 9, by setting the first timer, if a bearer is established between the called terminal and the called core network device during the operation of the first timer, the called terminal can carry local sendrecv when sending the 200OK (Update) message, and send a 180Ringing message after sending the 200OK (Update) message. Since the 200OK (Update) message carries local sendrecv, even if the interval between the sending of the 200OK (Update) message and the 180Ringing message is too short, it will not cause disorder, so that the calling core network device can smoothly forward the voice packet, reducing the probability of silent call.

[0485] Alternatively, as another implementation, if the called terminal does not receive a voice bearer establishment message from the called core network device during the first timer's execution, after the first timer expires, the called terminal may proceed to step 713-2. Furthermore, the called terminal must wait for a voice bearer to be established with the called core network device. For example, if steps 712a and 712b occur after the first timer expires, the called terminal may wait until the voice bearer is established before proceeding to step 714.

[0486] That is, if the voice bearer establishment message from the called core network device is not received during the first timer, after step 711c, the following steps (step 714-1, step 712c, step 712d) are performed instead of the above steps 712a, 712b, and step 713-1:

[0487] In step 714-1, after the first timer expires, the called terminal sends a third response message (corresponding to the third response message in step 604a above) to the called core network device. The third response message carries a first parameter (e.g., the value of the first parameter is local none). The first parameter indicates that no voice bearer has been established between the called terminal and the called core network device.

[0488] In step 714-2, the called core network device forwards the third response message to the calling core network device.

[0489] Step 714-3: After receiving the third response message, the calling core network device closes the media forwarding port.

[0490] Step 714 - 4 : The calling core network device forwards the third response message to the calling terminal.

[0491] Exemplarily, the third response message is a 200OK(Update) message. Because a voice bearer has not yet been established between the called terminal and the called core network device, the 200OK(Update) message carries the "local none" field. This field indicates that a voice bearer has not yet been established between the called terminal and the called core network device. Upon receiving the 200OK(Update) message, the calling core network device closes the media forwarding port based on the "local none" condition.

[0492] Step 712c: The called core network device sends a voice bearer establishment message on the called side to the called terminal.

[0493] Step 712d: The called terminal sends a voice bearer establishment completion message on the called side to the called core network device.

[0494] It should be understood that the messages involved in step 712c and step 712d are similar, the difference being the timing of occurrence. Step 712c and step 712d occur after the first timer expires. The explanation of each message involved in step 712c and step 712d is not repeated here.

[0495] In the process shown in Figure 9, a first timer is set. If the called terminal does not receive a voice bearer establishment message during the first timer's duration, the called terminal can send a 200OK(Update) message with the local none flag. After establishing a voice bearer with the called core network device, the called terminal can then send a 180Ringing message. This increases the interval between the 200OK(Update) and 180Ringing messages, reducing the probability of them arriving out of order at the calling core network. This allows the calling core network device to smoothly forward voice packets, reducing the likelihood of silent calls.

[0496] It should be noted that the steps shown in FIG9 are merely examples of a call connection establishment process, and the embodiments of the present application are not limited thereto.

[0497] It should be understood that the examples in Figures 5 to 9 are merely for ease of understanding and are not intended to limit the embodiments of the present application to the examples shown in the figures. In fact, those skilled in the art can perform equivalent transformations based on the examples in Figures 5 to 9 to obtain more implementations.

[0498] Voice packets between the calling and called terminals must be forwarded through the core network. If the voice packets are successfully forwarded by the network, the call between the called and calling terminals will function normally, without any silent calls. To avoid silent calls between the calling and called terminals, this application also provides another embodiment in which the calling core network device determines whether to change the status of the media forwarding port.

[0499] Optionally, the calling core network device receives a ringing message (i.e., a 180Ringing message) from the called party; after receiving the ringing message, the calling core network device opens a media forwarding port according to the ringing message. The calling core network device receives a response message (such as the aforementioned first response message, which carries "local none") sent by the called terminal through the called core network device, and the calling core network device does not use the "local none" media forwarding port in the response message.

[0500] That is to say, after the calling core network device receives the ringing message sent by the called terminal through the called core network device, it will open the media forwarding port. Even if a response message is received later, the forwarding status will no longer be modified according to the parameters carried in the response message. Instead, the media forwarding port will remain open to ensure that the voice packet can be forwarded smoothly until the call ends.

[0501] For example, the calling core network device first receives a 180Ringing message and opens the media forwarding port based on it. Subsequently, the calling core network device receives a 200OK(Update) message containing the message "Local None." At this point, the calling core network device does not close the media forwarding port based on the message "Local None." Instead, it maintains the media forwarding port open to ensure smooth forwarding of voice packets, reducing the likelihood of silent calls between the calling and called terminals.

[0502] The above description, in conjunction with Figures 1 to 9 , details the method for call connection provided by an embodiment of the present application. The following description details the device embodiment of the present application in conjunction with Figure 10 . It should be understood that the device for call connection in an embodiment of the present application can execute the various methods for call connection in the aforementioned embodiments of the present application. For the specific operating processes of the various products below, reference can be made to the corresponding processes in the aforementioned method embodiments.

[0503] Figure 10 is a schematic block diagram of an apparatus 800 for call connection according to an embodiment of the present application. It should be understood that the apparatus 800 can execute the method executed by the called terminal in the methods for call connection shown in Figures 5 to 9 .

[0504] As shown in FIG. 10 , the apparatus 800 includes a transceiver unit 810 and a processing unit 820 .

[0505] Exemplarily, the apparatus 800 is used to execute the method performed by the called terminal in FIG5 and FIG6 , which specifically includes:

[0506] The transceiver unit 810 is used to receive a session invitation from a calling terminal, where the session invitation is used to request to establish a voice call with the called terminal;

[0507] The transceiver unit 810 is further configured to send a request response message to the calling terminal, where the request response message is a response to the session invitation and is configured to indicate that the called terminal has received the session invitation;

[0508] The transceiver unit 810 is further configured to receive an update message from the called core network device;

[0509] The transceiver unit 810 is further configured to receive a switching instruction from a called core network device, wherein the switching instruction is used to notify the called terminal to switch from the first communication standard to the second communication standard;

[0510] The processing unit 820 is configured to switch from the first communication standard to the second communication standard according to the switching instruction;

[0511] The transceiver unit 810 is further configured to send a first response message after receiving the update message and before the tracking area update TAU is completed, where the first response message is a response to the update message, and the first response message is used to indicate that the called terminal has received the update message, and the first response message carries a first parameter, and the first parameter indicates that no voice bearer has been established between the called terminal and the called core network device;

[0512] The transceiver unit 810 is further configured to send a ringing message after sending the first response message, where the ringing message is used to notify the calling terminal that the called terminal has started ringing.

[0513] Optionally, as an embodiment, the transceiver unit 810 is used to send a first response message after receiving the update message and before the tracking area update TAU is completed, including: sending the first response message after receiving the switching indication and after switching from the first communication standard to the second communication standard, and before the tracking area update TAU is completed.

[0514] Optionally, as an embodiment, the transceiver unit 810 is further configured to receive a voice bearer establishment message from the called core network device after sending the first response message and before sending the ringing message, wherein the voice bearer establishment message is used to request establishment of a voice bearer under the second communication standard with the called terminal;

[0515] The processing unit 820 is configured to establish a voice bearer with the called terminal according to the voice bearer establishment message;

[0516] The transceiver unit 810 is further configured to send a voice bearer establishment completion message to the called core network device, where the voice bearer establishment completion message indicates that a voice bearer has been established between the called terminal and the called core network device.

[0517] Optionally, as an embodiment, the transceiver unit 810 is further configured to send a first request message after sending the first response message, where the first request message is used to request updating the tracking area;

[0518] The transceiver unit 810 is further configured to receive a TAU accept message from the called core network device, where the TAU accept message is used to respond to the first request message;

[0519] The transceiver unit 810 is further configured to send a TAU completion message to the called core network device, where the TAU completion message indicates that the tracking area update process is completed.

[0520] Optionally, the first response message is a 200OK message.

[0521] Optionally, the value of the first parameter is local none.

[0522] Alternatively, illustratively, the apparatus 800 is configured to execute the method performed by the called terminal in FIG8 and FIG9 , specifically comprising:

[0523] The transceiver unit 810 is used to receive a session invitation from a calling terminal, where the session invitation is used to request to establish a voice call with the called terminal;

[0524] The transceiver unit 810 is further configured to send a request response message to the calling terminal, where the request response message is a response to the session invitation and is configured to indicate that the called terminal has received the session invitation;

[0525] The transceiver unit 810 is further configured to receive an update message from the called core network device;

[0526] The processing unit 820 is configured to start a first timer after receiving the update message;

[0527] The transceiver unit 810 is further configured to receive a switching instruction within the first timer, wherein the switching instruction is used to notify the called terminal to switch from the first communication standard to the second communication standard;

[0528] The processing unit 820 is further configured to switch from the first communication standard to the second communication standard according to the switching instruction;

[0529] The transceiver unit 810 is further configured to, when the called terminal receives a voice bearer establishment message from the called core network device after switching from the first communication standard to the second communication standard within the first timer, and when a voice bearer is established between the called terminal and the called core network device after receiving the voice bearer establishment message, send a second response message to the called core network device, wherein the second response message is a response to the update message, and the second response message is used to indicate that the called terminal has received the update message, and the second response message carries a second parameter, and the second parameter indicates that a voice bearer has been established between the called terminal and the core network;

[0530] The transceiver unit 810 is further configured to send a ringing message after sending the second response message, where the ringing message is used to notify the calling terminal that the called terminal has started ringing.

[0531] Optionally, the duration of the first timer is greater than a first time threshold and less than a second time threshold, and the second time threshold is related to the duration of a timer related to establishing a voice bearer on the called core network side.

[0532] Optionally, as an embodiment, the transceiver unit 810 is further configured to receive a voice bearer establishment message from the called core network device within the first timer;

[0533] The transceiver unit 810 is further configured to send a voice bearer establishment completion message to the called core network device within the first timer.

[0534] Optionally, as an embodiment, the transceiver unit 810 is further configured to, in response to the called terminal not receiving a voice bearer establishment message from the called core network device within the first timer, the called terminal and the core network device sending a third response message, the third response message being a response to the update message, the third response message being used to indicate that the called terminal has received the update message, the third response message carrying a first parameter, the first parameter indicating that the called terminal and the called core network device have not established a voice bearer;

[0535] The transceiver unit 810 is further configured to send a ringing message to the called core network device after sending the third response message, where the ringing message is used to notify the calling terminal that the called terminal has started ringing.

[0536] Optionally, as an embodiment, the transceiver unit 810 is also used to receive a voice bearer establishment message from the called core network device after sending the third response message to the called core network device and before sending a ringing message to the called core network device; and send a voice bearer establishment completion message to the called core network device.

[0537] Optionally, as an embodiment, the value of the first parameter is local none.

[0538] Optionally, as an embodiment, the value of the second parameter is local sendrecv.

[0539] Optionally, as an embodiment, the first communication standard is a 5G standard; the second communication standard is an LTE standard; or,

[0540] The switching indication is an EPSFB switching indication.

[0541] In one possible example, the transceiver unit 810 may be implemented by a transceiver. The processing unit 820 may be implemented by a processor or a processing unit. It should be understood that the apparatus 800 is embodied in the form of a functional unit. The term "unit" herein may be implemented in the form of software and / or hardware, and this is not specifically limited in the present embodiment.

[0542] For example, a "unit" may be a software program, a hardware circuit, or a combination of the two that implements the above functions. The hardware circuit may include an application specific integrated circuit (ASIC), an electronic circuit, a processor (such as a shared processor, a dedicated processor, or a group processor, etc.) that executes one or more software or firmware programs and a memory, an integrated logic circuit, and / or other suitable devices that can provide the above functions.

[0543] FIG11 shows a schematic structural diagram of an electronic device 1000 suitable for the present application.

[0544] The electronic device 1000 may include a processor 110, an external memory interface 120, an internal memory 121, a universal serial bus (USB) interface 130, a charging management module 140, a power management module 141, a battery 142, an antenna 1, an antenna 2, a mobile communication module 150, a wireless communication module 160, an audio module 170, a speaker 170A, a receiver 170B, a microphone 170C, an earphone interface 170D, a sensor module 180, a button 190, a motor 191, an indicator 192, a camera 193, a display screen 194, and a subscriber identification module (SIM) card interface 195, etc. The sensor module 180 may include a pressure sensor 180A, a gyroscope sensor 180B, an air pressure sensor 180C, a magnetic sensor 180D, an acceleration sensor 180E, a distance sensor 180F, a proximity light sensor 180G, a fingerprint sensor 180H, a temperature sensor 180J, a touch sensor 180K, an ambient light sensor 180L, a bone conduction sensor 180M, etc.

[0545] It should be noted that the structure shown in FIG11 does not constitute a specific limitation on the electronic device 1000. In other embodiments of the present application, the electronic device 1000 may include more or fewer components than those shown in FIG11, or the electronic device 1000 may include a combination of some of the components shown in FIG11, or the electronic device 1000 may include sub-components of some of the components shown in FIG11. The components shown in FIG11 may be implemented in hardware, software, or a combination of software and hardware.

[0546] The processor 110 may include one or more processing units. For example, the processor 110 may include at least one of the following processing units: an application processor (AP), a modem processor, a graphics processing unit (GPU), an image signal processor (ISP), a controller, a video codec, a digital signal processor (DSP), a baseband processor, and a neural-network processing unit (NPU). The different processing units may be independent devices or integrated devices.

[0547] The controller can generate operation control signals according to the instruction operation code and timing signal to complete the control of instruction fetching and execution.

[0548] Processor 110 may also include a memory for storing instructions and data. In some embodiments, the memory in processor 110 is a cache memory. This memory can store instructions or data that have just been used or are being recycled by processor 110. If processor 110 needs to use the same instruction or data again, it can directly access the memory. This avoids duplicate accesses, reduces processor 110 latency, and thus improves system efficiency.

[0549] In some embodiments, the processor 110 may include one or more interfaces. For example, the processor 110 may include at least one of the following interfaces: an inter-integrated circuit (I2C) interface, an inter-integrated circuit sound (I2S) interface, a pulse code modulation (PCM) interface, a universal asynchronous receiver / transmitter (UART) interface, a mobile industry processor interface (MIPI), a general-purpose input / output (GPIO) interface, a SIM interface, and a USB interface.

[0550] In some embodiments, the processor 110 is configured to call a communication module to receive a session invitation from a calling terminal, where the session invitation is used to request to establish a voice call with the called terminal; send a request response message to the calling terminal, where the request response is a response to the session invitation and is used to indicate that the called terminal has received the session invitation message; receive an update message from a called core network device; receive a switching indication, where the switching indication is used to notify the called terminal to switch from a first communication standard to a second communication standard; switch from the first communication standard to the second communication standard according to the switching indication; after receiving the update message and before a tracking area update TAU is completed, send a first response message, where the first response message is a response to the update message and is used to indicate that the called terminal has received the update message, and the first response message carries a first parameter, where the first parameter indicates that no voice bearer has been established between the called terminal and the called core network device; and after sending the first response message, send a ringing message, where the ringing message is used to notify the calling terminal that the called terminal has started ringing.

[0551] In other embodiments, the processor 110 is used to call the communication module to receive a session invitation from the calling terminal, wherein the session invitation is used to request to establish a voice call with the called terminal; send a request response message to the calling terminal, wherein the request response message is a response to the session invitation and is used to indicate that the called terminal has received the session invitation; receive an update message from the called core network device; after receiving the update message, start a first timer; within the first timer, the called terminal receives a switching indication, wherein the switching indication is used to notify the called terminal to switch from the first communication standard to the second communication standard; switch from the first communication standard to the second communication standard according to the switching indication; within the first timer, the called terminal receives an incoming call after switching from the first communication standard to the second communication standard. A voice bearer establishment message is sent from the called core network device, and a voice bearer is established between the called terminal and the called core network device after receiving the voice bearer establishment message. The called terminal sends a second response message to the called core network device, where the second response message is a response to the update message. The second response message is used to indicate that the called terminal has received the update message. The second response message carries a second parameter, which indicates that a voice bearer has been established between the called terminal and the called core network device. The voice bearer establishment message is used to request to establish a voice bearer under the second communication standard with the called terminal; after the called terminal sends the second response message, it sends a ringing message, where the ringing message is used to notify the calling terminal that the called terminal has started ringing.

[0552] 11 is merely a schematic illustration and does not limit the connection relationship between the modules of the electronic device 1000. Optionally, the modules of the electronic device 1000 may also adopt a combination of the multiple connection modes in the above embodiments.

[0553] The wireless communication function of the electronic device 1000 can be implemented through components such as the antenna 1, the antenna 2, the mobile communication module 150, the wireless communication module 160, the modem processor, and the baseband processor.

[0554] Electronic device 1000 can implement display functions using a GPU, display screen 194, and an application processor. A GPU is a microprocessor for image processing that connects display screen 194 and the application processor. The GPU is used to perform mathematical and geometric calculations for graphics rendering. Processor 110 may include one or more GPUs that execute program instructions to generate or modify display information.

[0555] Display screen 194 can be used to display images or videos. Display screen 194 includes a display panel. The display panel can use a liquid crystal display (LCD), an organic light-emitting diode (OLED), an active-matrix organic light-emitting diode (AMOLED), a flexible light-emitting diode (FLED), a mini light-emitting diode (Mini LED), a micro light-emitting diode (Micro LED), a micro OLED, or a quantum dot light-emitting diode (QLED). In some embodiments, electronic device 1000 may include one or N display screens 194, where N is a positive integer greater than 1.

[0556] The electronic device 1000 can implement a shooting function through an ISP, a camera 193, a video codec, a GPU, a display screen 194, and an application processor.

[0557] The digital signal processor is used to process digital signals. In addition to processing digital image signals, it can also process other digital signals. For example, when the electronic device 1000 selects a frequency point, the digital signal processor is used to perform Fourier transform on the frequency point energy.

[0558] The electronic device 1000 can implement audio functions, such as music playback and recording, through the audio module 170, the speaker 170A, the receiver 170B, the microphone 170C, the headphone jack 170D, and the application processor.

[0559] It can be understood that the method for call connection in the embodiment of the present application can be applied to the electronic device shown in FIG11 . For specific implementation steps, reference can be made to the introduction of the method embodiment above and will not be repeated here.

[0560] According to the method provided in the embodiment of the present application, the present application also provides a communication system, which includes the aforementioned called terminal, calling terminal, called core network device, calling core network device, and optionally, calling access network device and called access network device.

[0561] The present invention provides a chip system comprising one or more processors configured to retrieve and execute instructions stored in a memory, thereby executing the method of the present invention. The chip system may be composed of a chip or may include a chip and other discrete devices.

[0562] Among them, the chip system may include an input circuit or interface for sending information or data, and an output circuit or interface for receiving information or data.

[0563] The present application also provides a computer program product, which, when executed by a processor, implements the method described in any method embodiment of the present application.

[0564] The computer program product can be stored in a memory and finally converted into an executable target file that can be executed by a processor through preprocessing, compilation, assembly and linking.

[0565] The present application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a computer, implements the method described in any method embodiment of the present application. The computer program can be a high-level language program or an executable target program.

[0566] The computer-readable storage medium may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memories. 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 synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link dynamic random access memory (SLDRAM), and direct rambus RAM (DR RAM).

[0567] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described devices and equipment and the technical effects produced can refer to the corresponding processes and technical effects in the aforementioned method embodiments, and will not be repeated here.

[0568] In the several embodiments provided in this application, the disclosed systems, devices and methods can be implemented in other ways. For example, some features of the method embodiments described above can be ignored or not executed. The device embodiments described above are merely schematic, and the division of units is only a logical function division. There may be other division methods in actual implementation, and multiple units or components may be combined or integrated into another system. In addition, the coupling between the units or the coupling between the components may be direct coupling or indirect coupling, and the above coupling includes electrical, mechanical or other forms of connection.

[0569] It should be understood that in the various embodiments of the present application, the size of the serial number of each process does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0570] Additionally, the terms "system" and "network" are often used interchangeably. The term "and / or" in this document simply describes a relationship between related objects, indicating that three possible relationships exist. For example, "A and / or B" can mean: A exists alone, A and B exist simultaneously, or B exists alone. Furthermore, the character " / " in this document generally indicates an "or" relationship between the related objects.

[0571] The terms (or numbers) "first", "second", ... etc. that appear in the embodiments of the present application are only used for descriptive purposes, that is, they are only used to distinguish different objects, such as different "response messages", etc., and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first", "second", ... etc. may explicitly or implicitly include one or more features. In the description of the embodiments of the present application, "at least one (item)" refers to one or more. "Multiple" means two or more. "At least one of the following (item)" or similar expressions refers to any combination of these items, including any combination of a single (item) or plural (items).

[0572] In short, the above description is only a preferred embodiment of the technical solution of this application and is not intended to limit the scope of protection of this application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of this application shall be included in the scope of protection of this application.

Claims

1. A method for call connection, characterized in that: The method is applied to the called terminal, and the method includes: receiving a session invitation from a calling terminal, wherein the session invitation is used to request to establish a voice call with the called terminal; Sending a request response message to the calling terminal, where the request response message is a response to the session invitation and is used to indicate that the called terminal has received the session invitation; Receive update messages from the called core network device; receiving a switching instruction, wherein the switching instruction is used to notify the called terminal to switch from the first communication standard to the second communication standard; Switching from the first communication standard to the second communication standard according to the switching instruction; After receiving the update message and before completing the tracking area update (TAU), sending a first response message, where the first response message is a response to the update message, the first response message is used to indicate that the called terminal has received the update message, and the first response message carries a first parameter, where the first parameter indicates that no voice bearer has been established between the called terminal and the called core network device; After the called terminal sends the first response message, the called terminal sends a ringing message, where the ringing message is used to notify the calling terminal that the called terminal has started ringing.

2. The method according to claim 1, characterized in that The sending the first response message after receiving the update message and before the tracking area update TAU is completed includes: The called terminal sends the first response message after receiving the switching instruction and switching from the first communication standard to the second communication standard, and before the tracking area update TAU is completed.

3. The method according to claim 1 or 2, characterized in that After the called terminal sends the first response message and before sending the ringing message, the method further includes: receiving a voice bearer establishment message from a called core network device, wherein the voice bearer establishment message is used to request establishment of a voice bearer under the second communication standard with the called terminal; Establishing a voice bearer with the called terminal according to the voice bearer establishment message; A voice bearer establishment completion message is sent to the called core network device, where the voice bearer establishment completion message is used to indicate that a voice bearer has been established between the called terminal and the called core network device.

4. The method according to any one of claims 1 to 3, characterized in that After sending the first response message, the method further includes: Sending a first request message, where the first request message is used to request updating of a tracking area; receiving a TAU accept message from the called core network device, where the TAU accept message is used to respond to the first request message; A TAU completion message is sent to the called core network device, where the TAU completion message indicates that the tracking area update process is completed.

5. The method according to any one of claims 1 to 4, characterized in that The first response message is a 200OK message.

6. The method according to any one of claims 1 to 5, characterized in that The value of the first parameter is local none.

7. A communication method, characterized in that: The method is applied to the called terminal, and the method includes: Receive a session invitation from the calling terminal, the session invitation is used to request to establish a voice call with the called terminal call; Sending a request response message to the calling terminal, where the request response is a response to the session invitation and is used to indicate that the called terminal has received the session invitation message; Receive update messages from the called core network device; After receiving the update message, starting a first timer; The called terminal receives a switching instruction within the first timer, where the switching instruction is used to notify the called terminal to switch from the first communication standard to the second communication standard; The called terminal switches from the first communication standard to the second communication standard according to the switching instruction; Within the first timer, the called terminal receives a voice bearer establishment message from the called core network device after switching from the first communication standard to the second communication standard, and a voice bearer is established between the called terminal and the called core network device after receiving the voice bearer establishment message, the called terminal sends a second response message to the called core network device, where the second response message is a response to the update message, the second response message is used to indicate that the called terminal has received the update message, the second response message carries a second parameter, the second parameter indicates that a voice bearer has been established between the called terminal and the called core network device, and the voice bearer establishment message is used to request to establish a voice bearer under the second communication standard with the called terminal; After the called terminal sends the second response message, the called terminal sends a ringing message, where the ringing message is used to notify the calling terminal that the called terminal has started ringing.

8. The method according to claim 7, characterized in that The duration of the first timer is less than a second time threshold, and the second time threshold is related to the duration of a timer on the called core network side related to establishing a voice bearer.

9. The method according to claim 7 or 8, characterized in that Within the first timer, the method further includes: Receive a voice bearer establishment message from the called core network device; Send a voice bearer establishment completion message to the called core network device.

10. The method according to claim 7 or 8, characterized in that The method further comprises: In response to the called terminal not receiving a voice bearer establishment message from the called core network device within the first timer, the called terminal sending a third response message to the called core network device, where the third response message is a response to the update message, the third response message is used to indicate that the called terminal has received the update message, and the third response message carries a first parameter, where the first parameter indicates that no voice bearer has been established between the called terminal and the called core network device; After sending the third response message, a ringing message is sent to the called core network device, where the ringing message is used to notify the calling terminal that the called terminal has started ringing.

11. The method according to claim 10, characterized in that After sending the third response message to the called core network device and before sending the ringing message to the called core network device, the method further includes: Receive a voice bearer establishment message from the called core network device; Send a voice bearer establishment completion message to the called core network device.

12. The method according to claim 10 or 11, characterized in that The value of the first parameter is local none.

13. The method according to any one of claims 7 to 11, characterized in that The value of the second parameter is local sendrecv.

14. The method according to any one of claims 1 to 13, characterized in that The method further comprises at least one of the following: The first communication standard is the 5G standard; The second communication standard is the LTE standard; or, The switching indication is an EPSFB switching indication.

15. An electronic device, characterized in that: The electronic device comprises a processor and a memory, wherein the processor and the memory are coupled, and the memory is used to store a computer program. When the computer program is executed by the processor, the electronic device executes the method according to any one of claims 1 to 14.

16. A chip, characterized in that: The method comprises a processor, wherein when the processor executes instructions, the processor performs the method according to any one of claims 1 to 14.

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