Communication method and apparatus

Abstract

This application provides a communication method and apparatus, relating to the field of wireless communication technology, which can avoid the problem of terminal devices being unable to perform voice services after accessing a visited network due to their lack of support for Voice over New Radio (VoNR). The method includes: the terminal device sending first information to the core network equipment of its home network. The first information is used to indicate that the terminal device supports VoNR or inter-network roaming, or, the first information is used to request Public Land Mobile Network (PLMN) information of the visited network, wherein the operator of the visited network is different from the operator of the terminal device's home network. Subsequently, the terminal device receives the PLMN information of the visited network from the core network equipment.

Description

[0001] This application claims priority to Chinese Patent Application No. 202111618289.X, filed on December 27, 2021, entitled "A Method and Apparatus for Registration Transmission", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of wireless communication, and more particularly to a communication method and apparatus. Background Technology

[0003] In the early stages of 5G standalone (SA) network deployment, operator networks and terminal equipment do not support Voice over New Radio (VoNR). Terminal equipment needs to fall back to the 4G network via the evolved packet system (EPS) to provide voice services. Performing EPS fallback requires the 5G core network element access and mobility management function (AMF) to open an interface with the 4G core network element mobility management entity (MME) to complete the fallback process from 5G to 4G and establish a voice transmission channel in the 4G network.

[0004] However, in 5G core network cross-network roaming scenarios, the AMF of the visiting network and the MME of the home network do not have an interface. Therefore, terminal devices that do not support VONR cannot establish a voice transmission channel to 4G by executing the EPS fallback process, and thus cannot carry out voice services, resulting in a poor user experience. Summary of the Invention

[0005] This application provides a communication method and apparatus that can avoid the problem of being unable to perform voice services after the terminal device accesses the visited network because it does not support New Radio Voice over NR.

[0006] To achieve the above objectives, the embodiments of this application adopt the following technical solutions:

[0007] Firstly, this application provides a communication method, the execution subject of which can be a terminal device or a chip applied in the terminal device. The following description uses a terminal device as the execution subject. The method includes: the terminal device sending first information to the core network equipment of its home network. The first information is used to instruct the terminal device to support Voice over New Radio (VoNR) or inter-network roaming. Alternatively, the first information is used to request Public Land Mobile Network (PLMN) information of a visited network, the operator of which is different from the operator of the terminal device's home network. Subsequently, the terminal device receives the PLMN information of the visited network from the core network equipment.

[0008] Thus, the core network equipment only sends the PLMN information of the visited network to the terminal device when it determines that the terminal device supports VoNR or when the terminal device requests to obtain the PLMN information of the visited network. Even if the operator of the visited network is different from the operator of the home network, the terminal device can still access the visited network and perform voice services through the visited network, avoiding the problem that the terminal device cannot perform voice services after accessing the visited network because it does not support VoNR.

[0009] In one possible design, the terminal device sends first information to the core network device of its home network via an attach request message. This allows the terminal device to send first information to the core network device during the 4G registration process, enabling the core network device to know that the terminal device supports VoNR or that the terminal device is requesting to obtain the PLMN information of the visited network. This avoids the core network device sending the PLMN information of the visited network to terminal devices that do not support VoNR.

[0010] In one possible design, the terminal device sends first information to the core network equipment of its home network via a registration request message. This allows the terminal device to send first information to the core network equipment during the 5G registration process, enabling the core network equipment to know that the terminal device supports VoNR, or for the terminal device to request PLMN information of the visited network. This avoids the core network equipment sending PLMN information of the visited network to terminal devices that do not support VoNR.

[0011] In one possible design, the first piece of information is carried in a field indicating the network capabilities of the user equipment.

[0012] In one possible design, the first information is carried in preset bits, which include bits in fixed bits of a field indicating the network capabilities of the user equipment, such as bits that were originally in a spare state.

[0013] In one possible design, the first information is carried in one of the following: the user equipment network capability field, or the user equipment network capability field of the N1 interface.

[0014] In one possible design, the first information is carried in one of the following: a mobility management capability field, or a user equipment network capability field of the S1 interface.

[0015] In one possible design, the terminal device sends the first information to the core network equipment of its home network via a secure mode completion message. This secure mode completion message is protected by an encryption key, thereby reducing the possibility of the first information being tampered with or leaked, and improving the reliability of information transmission.

[0016] In one possible design, the terminal device sends first information to the core network device of the home network via a Tracking Area Update (TAU) request message. This allows the terminal device to send first information to the core network device during the TAU process, enabling the core network device to know that the terminal device supports VoNR, or that the terminal device is requesting to obtain the PLMN information of the visited network. This avoids the core network device sending the PLMN information of the visited network to terminal devices that do not support VoNR.

[0017] Secondly, this application provides a communication method, the execution subject of which can be a core network device or a chip applied in the core network device. The following description uses a core network device as the execution subject. The method includes: the core network device receiving first information from a terminal device. The first information is used to instruct the terminal device to support Voice over New Radio (VoNR) or inter-network roaming. Alternatively, the first information is used to request Public Land Mobile Network (PLMN) information of a visited network, where the operator of the visited network is different from the operator of the terminal device's home network, and the core network device is the core network device of the terminal device's home network. Then, the core network device sends the PLMN information of the visited network to the terminal device according to the first information.

[0018] In one possible design, the core network device receives the first information from the terminal device via an attach request message.

[0019] In one possible design, the core network device receives the first information from the terminal device via a registration request message.

[0020] In one possible design, the first piece of information is carried in a field indicating the network capabilities of the user equipment.

[0021] In one possible design, the first information is carried in preset bits, which include bits in a field indicating the network capabilities of the user equipment.

[0022] In one possible design, the first information is carried in one of the following: the user equipment network capability field, or the user equipment network capability field of the N1 interface.

[0023] In one possible design, the first information is carried in one of the following: a mobility management capability field, or a user equipment network capability field of the S1 interface.

[0024] In one possible design, the core network equipment completes the message reception of the first information from the terminal equipment in a secure mode.

[0025] In one possible design, the core network device receives the first information from the terminal device via a Tracking Area Update (TAU) request message.

[0026] Thirdly, this application provides a communication method. The execution subject of this method can be a core network device or a chip applied in the core network device. The following description uses a core network device as the execution subject. The method includes: the core network device determining that the terminal device supports Voice over New Radio (VoNR), wherein the core network device is the core network device of the terminal device's home network. Then, the core network device sends Public Land Mobile Network (PLMN) information of the visited network to the terminal device, wherein the operator of the visited network is different from the operator of the terminal device's home network.

[0027] Thus, the core network equipment only sends the visited network's PLMN information to the terminal device after confirming that the terminal device supports VoNR functionality. Even if the operator of the visited network is different from the operator of the home network, the terminal device can still access the visited network and perform voice services through the visited network, avoiding the problem of being unable to perform voice services after accessing the visited network due to the terminal device's lack of VoNR support.

[0028] In one possible design, the communication method in this embodiment further includes: a core network device receiving radio capability information from an access network device. The radio capability information indicates the radio capabilities of the terminal device. The core network device determining that the terminal device supports VoNR includes: the core network device determining that the terminal device supports VoNR based on the radio capability information.

[0029] In this way, core network equipment can independently determine whether terminal equipment supports VoNR function based on radio capability information.

[0030] In one possible design, the communication method of this application embodiment further includes: when the core network device does not save the radio capability information, the core network device sends an initial context establishment request to the access network device, wherein the initial context establishment request does not carry the radio capability information, so that the access network device provides the radio capability information to the core network device.

[0031] In one possible design, the communication method of this application embodiment further includes: a core network device receiving indication information from an access network device, wherein the indication information indicates that the terminal device supports VoNR. The core network device determining that the terminal device supports VoNR includes: the core network device determining that the terminal device supports VoNR based on the indication information.

[0032] In this way, the access network device determines that the terminal device supports the VoNR function, and then informs the core network device so that the core network device knows that the terminal device supports the VoNR function.

[0033] In one possible design, the core network device receives indication information from the access network device via a radio capability matching response message. That is, the radio capability matching response message carries the aforementioned indication information, thereby enabling the core network device to obtain it.

[0034] In one possible design, the communication method of this application embodiment further includes: a core network device sending a first request message to an access network device. The first request message requests to obtain indication information, so that the access network device responds to the first request message by providing indication information to the core network device.

[0035] In one possible design, the core network device sends a first request message to the access network device via a terminal device capability information indication message. That is, the capability information indication message carries the aforementioned first request message, thereby sending the aforementioned indication information to the access network device.

[0036] In one possible design, the core network device sends the PLMN information of the visited network to the terminal device through a registration acceptance message, so that the terminal device can obtain the PLMN information of the visited network through the registration process, effectively preventing terminal devices that do not support VoNR from receiving the PLMN information of the visited network.

[0037] In one possible design, the core network equipment includes a Mobility Management Entity (MME) or a Mobility Management Function (AMF) element.

[0038] Fourthly, this application provides a communication device, which can be a terminal device in the first aspect or any possible design of the first aspect, or a chip that implements the functions of the terminal device described above; the communication device includes modules, units, or means that implement the methods described above, which can be implemented in hardware, software, or by hardware executing corresponding software. The hardware or software includes one or more modules or units corresponding to the functions described above.

[0039] The communication device includes a processing unit, a transmitting unit, and a receiving unit. The processing unit controls the transmitting unit to send first information to the core network equipment of the home network. This first information indicates that the communication device supports Voice over New Radio (VoNR) or inter-network roaming, or it requests Public Land Mobile Network (PLMN) information of the visited network, where the operator of the visited network is different from the operator of the communication device's home network. The processing unit also controls the receiving unit to receive the PLMN information of the visited network from the core network equipment.

[0040] In one possible design, the sending unit is specifically used to send first information to the core network device of the home network via an attach request message.

[0041] In one possible design, the sending unit is specifically used to send first information to the core network equipment of the home network via a registration request message.

[0042] In one possible design, the first piece of information is carried in a field indicating the network capabilities of the user equipment.

[0043] In one possible design, the first information is carried in preset bits, wherein the preset bits include bits in a field indicating the network capabilities of the user equipment.

[0044] In one possible design, the first information is carried in one of the following: the user equipment network capability field, or the user equipment network capability field of the N1 interface.

[0045] In one possible design, the first information is carried in one of the following: a mobility management capability field, or a user equipment network capability field of the S1 interface.

[0046] In one possible design, the sending unit is specifically used to send the first information to the core network device of the home network via a secure mode.

[0047] In one possible design, the sending unit is specifically used to send first information to the core network equipment of the home network via a Tracking Area Update TAU Request message.

[0048] Fifthly, this application provides a communication device, which can be a core network device in the second aspect or any possible design of the second aspect, or a chip that implements the functions of the core network device described above; the communication device includes modules, units, or means that implement the methods described above, which can be implemented in hardware, software, or by hardware executing corresponding software. The hardware or software includes one or more modules or units corresponding to the functions described above.

[0049] The communication device includes a processing unit, a transmitting unit, and a receiving unit. The processing unit controls the receiving unit to receive first information from a terminal device. This first information instructs the terminal device to support Voice over New Radio (VoNR) or inter-network roaming, or requests information about the Public Land Mobile Network (PLMN) of the visited network. The operator of the visited network is different from the operator of the terminal device's home network, and the communication device is a core network device of the terminal device's home network. The processing unit also controls the transmitting unit to send the visited network's PLMN information to the terminal device based on the first information.

[0050] In one possible design, the receiving unit is specifically used to receive first information from the terminal device via an attach request message.

[0051] In one possible design, the receiving unit is specifically used to receive first information from the terminal device via a registration request message.

[0052] In one possible design, the first piece of information is carried in a field indicating the network capabilities of the user equipment.

[0053] In one possible design, the first information is carried in preset bits, which include bits in a field indicating the network capabilities of the user equipment.

[0054] In one possible design, the first information is carried in one of the following: the user equipment network capability field, or the user equipment network capability field of the N1 interface.

[0055] In one possible design, the first information is carried in one of the following: a mobility management capability field, or a user equipment network capability field of the S1 interface.

[0056] In one possible design, the receiving unit is specifically used to receive the first information from the terminal device in a secure mode.

[0057] In one possible design, the receiving unit is specifically used to receive first information from the terminal device via a tracking area update TAU request message.

[0058] Sixthly, this application provides a communication device, which can be a core network device in the third aspect or any possible design of the third aspect, or a chip that implements the functions of the core network device described above; the communication device includes modules, units, or means that implement the methods described above, which can be implemented in hardware, software, or by hardware executing corresponding software. The hardware or software includes one or more modules or units corresponding to the functions described above.

[0059] The communication device includes a processing unit, a transmitting unit, and a receiving unit. The processing unit determines whether the terminal device supports Voice over New Radio (VoNR), and this communication device is the core network equipment of the terminal device's home network. The transmitting unit sends Public Land Mobile Network (PLMN) information of the visited network to the terminal device, wherein the operator of the visited network is different from the operator of the terminal device's home network.

[0060] In one possible design, the receiving unit is further configured to receive radio capability information from the access network device, wherein the radio capability information indicates the radio capability of the terminal device. The processing unit is configured to determine that the terminal device supports VoNR, including: determining that the terminal device supports VoNR based on the radio capability information.

[0061] In one possible design, the transmitting unit is further configured to send an initial context establishment request to the access network device when the communication device does not store radio capability information, wherein the initial context establishment request does not carry radio capability information.

[0062] In one possible design, the receiving unit is further configured to receive indication information from the access network device, wherein the indication information indicates that the terminal device supports VoNR. The processing unit is configured to determine that the terminal device supports VoNR, including: determining that the terminal device supports VoNR based on the indication information.

[0063] In one possible design, the receiving unit is specifically used to receive indication information from the access network device via a wireless capability matching response message.

[0064] In one possible design, the sending unit is further configured to send a first request message to the access network device, wherein the first request message requests to obtain indication information.

[0065] In one possible design, the sending unit is specifically used to send a first request message to the access network device via a terminal device capability information indication message.

[0066] In one possible design, the sending unit is specifically used to send PLMN information of the visited network to the terminal device by registering and receiving messages.

[0067] In one possible design, the communication device includes a Mobility Management Entity (MME) or a Mobility Management Function (AMF) element.

[0068] In a seventh aspect, embodiments of this application provide a communication device, including: a processor and a memory; the memory is used to store computer instructions, which, when executed by the processor, cause the communication device to perform the method executed by a terminal device in any of the above aspects or any possible designs of the above aspects. The communication device can be a terminal device in any of the above-described first aspects or any possible designs of the first aspect, or a chip implementing the functions of the aforementioned terminal device.

[0069] Eighthly, embodiments of this application provide a communication device, including: a processor; the processor is coupled to a memory for reading and executing instructions from the memory, so that the communication device performs a method as described in any of the above aspects or any possible designs of the terminal device in any of the above aspects. The communication device may be a terminal device as described in the first aspect or any possible designs of the first aspect, or a chip implementing the functions of the terminal device described above.

[0070] Ninthly, embodiments of this application provide a chip including a processing circuit and an input / output interface. The input / output interface is used to communicate with modules outside the chip; for example, the chip can be a chip that implements the terminal device functions described in the first aspect or any possible design of the first aspect. The processing circuit is used to run computer programs or instructions to implement the methods described in the first aspect or any possible design of the first aspect.

[0071] In a tenth aspect, embodiments of this application provide a communication device, including: a processor and a memory; the memory is used to store computer instructions, which, when executed by the processor, cause the communication device to perform the method executed by a core network device in any of the above-described aspects or any possible designs of the above-described aspects. The communication device may be a core network device in any of the above-described second aspects or any possible designs of the second aspect, or the communication device may be a core network device in any of the above-described third aspects or any possible designs of the third aspect, or a chip implementing the functions of the above-described core network device.

[0072] Eleventhly, embodiments of this application provide a communication device, including: a processor; the processor is coupled to a memory and is configured to read and execute instructions from the memory, so that the communication device performs a method as performed by a core network device in any of the above-described aspects or any possible designs of any of the above-described aspects. The communication device may be a core network device in any of the above-described second aspects or any possible designs of the second aspect, or the communication device may be a core network device in any of the above-described third aspects or any possible designs of the third aspect, or a chip implementing the functions of the above-described core network device.

[0073] In a twelfth aspect, embodiments of this application provide a chip including a processing circuit and an input / output interface. The input / output interface is used to communicate with modules outside the chip. For example, the chip can be a chip implementing the core network device functions in the second aspect or any possible design of the second aspect described above. The processing circuit is used to run computer programs or instructions to implement the methods in the second aspect or any possible design of the second aspect described above. Alternatively, the chip can be a chip implementing the core network device functions in the third aspect or any possible design of the third aspect described above. The processing circuit is used to run computer programs or instructions to implement the methods in the third aspect or any possible design of the third aspect described above.

[0074] In a thirteenth aspect, embodiments of this application provide a computer-readable storage medium storing instructions that, when executed on a computer, enable the computer to perform the methods of any of the preceding aspects.

[0075] In a fourteenth aspect, embodiments of this application provide a computer program product containing instructions that, when run on a computer, enable the computer to perform the method of any of the preceding aspects.

[0076] In a fifteenth aspect, embodiments of this application provide a circuit system including a processing circuit configured to perform the method as described in any of the preceding aspects.

[0077] In a sixteenth aspect, embodiments of this application provide a communication system including a core network device and an access network device. The access network device is configured to send first information to the core network device, wherein the first information indicates the radio capabilities of a terminal device, or indicates that the terminal device supports Voice over New Radio (VoNR). The core network device is configured to receive the first information from the access network device, wherein the core network device is the core network device of the terminal device's home network. The core network device is further configured to determine, based on the first information, that the terminal device supports VoNR. The core network device is also configured to send Public Land Mobile Network (PLMN) information of a visited network to the terminal device, wherein the operator of the visited network is different from the operator of the terminal device's home network.

[0078] The technical effects of any of the designs in aspects two through sixteen can be found in the beneficial effects of the corresponding methods provided above, and will not be repeated here. Attached Figure Description

[0079] Figure 1 A schematic diagram of the architecture of a communication system used in an embodiment of this application;

[0080] Figure 2 A schematic diagram of the architecture of another communication system used in an embodiment of this application;

[0081] Figure 3 A schematic diagram of the architecture of another communication system used in an embodiment of this application;

[0082] Figure 4 A schematic diagram of the architecture of another communication system used in an embodiment of this application;

[0083] Figure 5 A schematic diagram of the architecture of another communication system used in an embodiment of this application;

[0084] Figure 6 A flowchart illustrating a communication method provided in an embodiment of this application;

[0085] Figure 7a A flowchart illustrating another communication method provided in an embodiment of this application;

[0086] Figure 7b A flowchart illustrating yet another communication method provided in an embodiment of this application;

[0087] Figure 7c A flowchart illustrating yet another communication method provided in an embodiment of this application;

[0088] Figure 7d A flowchart illustrating yet another communication method provided in an embodiment of this application;

[0089] Figure 8 A flowchart illustrating yet another communication method provided in an embodiment of this application;

[0090] Figure 9 A flowchart illustrating yet another communication method provided in an embodiment of this application;

[0091] Figure 10a A flowchart illustrating yet another communication method provided in an embodiment of this application;

[0092] Figure 10b A flowchart illustrating yet another communication method provided in an embodiment of this application;

[0093] Figure 10c A flowchart illustrating yet another communication method provided in an embodiment of this application;

[0094] Figure 11 A flowchart illustrating yet another communication method provided in an embodiment of this application;

[0095] Figure 12a A flowchart illustrating yet another communication method provided in an embodiment of this application;

[0096] Figure 12bA flowchart illustrating yet another communication method provided in an embodiment of this application;

[0097] Figure 12c A flowchart illustrating yet another communication method provided in an embodiment of this application;

[0098] Figure 13 This is a schematic diagram of the structure of a communication device provided in an embodiment of this application;

[0099] Figure 14 This is a schematic diagram of another communication device provided in an embodiment of this application. Detailed Implementation

[0100] Figure 1 This is a schematic diagram of the architecture of a communication system provided in an embodiment of this application. Figure 1 As shown, the communication system includes terminal equipment, access network equipment, and core network.

[0101] The terminal equipment includes devices that provide voice and / or data connectivity to users. Specifically, it includes devices that provide voice connectivity to users, or devices that provide data connectivity to users, or devices that provide both voice and data connectivity to users. For example, it may include a handheld device with wireless connectivity or a processing device connected to a wireless modem. This terminal equipment can communicate with the core network via a radio access network (RAN), exchanging voice or data with the RAN, or interacting with the RAN for both voice and data. The terminal equipment may include user equipment (UE), wireless terminal equipment, mobile terminal equipment, device-to-device (D2D) terminal equipment, vehicle-to-everything (V2X) terminal equipment, machine-to-machine / machine-type communications (M2M / MTC) terminal equipment, Internet of Things (IoT) terminal equipment, subscriber unit, subscriber station, mobile station, remote station, access point (AP), remote terminal, access terminal, user terminal, user agent, or user device, etc. For example, it may include mobile phones (or "cellular" phones), computers with mobile terminal devices, portable, pocket-sized, handheld, or computer-embedded mobile devices, etc. Examples include personal communication service (PCS) phones, cordless phones, session initiation protocol (SIP) phones, wireless local loop (WLL) stations, and personal digital assistants (PDAs). It also includes limited devices, such as those with low power consumption, limited storage capacity, or limited computing power. Examples include information sensing devices such as barcode scanners, radio frequency identification (RFID), sensors, global positioning systems (GPS), and laser scanners.

[0102] The various terminal devices described above, if located in a vehicle (e.g., placed inside or installed inside a vehicle), can be considered as vehicle-mounted terminal devices, also known as on-board units (OBUs).

[0103] In this embodiment, the terminal device may further include a relay. Alternatively, it can be understood that anything capable of data communication with a base station can be considered a terminal device.

[0104] In this application embodiment, the device for implementing the functions of the terminal device can be the terminal device itself, or it can be a device capable of supporting the terminal device in implementing the functions, such as a chip system, which can be installed in the terminal device. In this application embodiment, the chip system can be composed of chips, or it can include chips and other discrete devices. In the technical solutions provided in this application embodiment, the terminal device is used as an example to illustrate the device for implementing the functions of the terminal.

[0105] Access network equipment can be access points for wireless or wired communication, such as base stations or base station controllers, wireless-fidelity (Wi-Fi) access points or Wi-Fi controllers, or fixed-line access points, etc. The base station can include various types of base stations, such as micro base stations (also known as small stations), macro base stations, relay stations, access points, etc., but this application embodiment does not specifically limit this. In the embodiments of this application, the base station may be a base transceiver station (BTS) in Global System for Mobile Communication (GSM), a base station (node ​​B) in Wideband Code Division Multiple Access (WCDMA), an evolved node B (eNB or e-NodeB) in Long Term Evolution (LTE), an eNB in ​​Internet of Things (IoT) or Narrow Band Internet of Things (NB-IoT), a base station in the fifth generation (5G) mobile communication network, or a future public land mobile network (PLMN). The embodiments of this application do not impose any limitations on this.

[0106] The core network includes various core network devices. For example, core network devices may include a mobility management entity (MME), as detailed in [link to relevant documentation]. Figure 2 The introduction further details this. For example, core network equipment can also include core access and mobility management (AMF) network elements; see [link to relevant documentation] for more information. Figure 3 Introduction. It should be understood that core network equipment may also include other network elements, such as user plane function (UPF) network elements, session management function (SMF) network elements, etc., which will not be elaborated here.

[0107] For example, Figure 2 This diagram illustrates the architecture of a fourth-generation (4G) communication system. The 4G system includes Evolved UMTS Territorial Radio Access Network (E-UTRAN) equipment, MME, Serving Gateway (SGW), Packet Data Network (PDN) Gateway (PGW), Policy and Charging Rules Function (PCRF) network elements, and Home Subscriber Server (HSS) network elements or equipment.

[0108] The terminal device accesses the E-UTRAN device via LTE-Uu, the E-UTRAN device communicates with the MME via S1-MME, the E-UTRAN device communicates with the SGW via S1-U, and different MMEs communicate with each other via S10. Figure 1 The example given is only an MME. The MME communicates with the HSS through S6a, the MME communicates with the SGW through S11, the PGW communicates with the PCRF network element through Gx, the PCRF network element communicates with the server through Rx, the SGW communicates with the PGW through S5, and the PGW accesses the server through SGi.

[0109] The E-UTRAN equipment is used to implement radio-related functions of the evolved network. The MME is responsible for mobility management on the control plane, including user context and mobility state management, and assigning temporary user identities. The SGW is the user plane anchor point between 3GPP access networks and serves as the interface for terminating E-UTRAN. The PGW is the user plane anchor point between 3GPP and non-3GPP access networks and serves as the interface for terminating external PDNs. PCRF network elements are used for policy control decisions and flow charging control functions. The HSS stores user subscription information. Servers provide Internet Protocol (IP) services, such as voice / video services and packet-switched streaming services (PSS) based on the Internet Protocol Multimedia Subsystem (IMS).

[0110] For example, Figure 3 This diagram illustrates the architecture of a fifth-generation (5G) communication system. The 5G communication system includes radio access network (RAN) equipment, UPF network elements, AMF network elements, SMF network elements, authentication server function (AUSF) network elements, network slice selection function (NSSF) network elements, network exposure function (NEF) network elements, network function repository function (NRF) network elements, policy control function (PCF) network elements, unified data management (UDM) network elements, unified data repository (UDR) network elements, application function (AF) network elements, or charging function (CHF) network elements, etc.

[0111] It should be noted that, Figure 3These are merely examples of network elements or entities in a 5G communication system. The 5G communication system may also include network data analytics function (NWDAF) network elements, etc. Figure 3 For network elements or entities not shown, this application embodiment does not specifically limit them.

[0112] Among them, such as Figure 3 As shown, the terminal device accesses the 5G network through the RAN device. The terminal device communicates with the AMF through the N1 interface (N1 for short); the RAN device communicates with the AMF network element through the N2 interface (N2 for short); the RAN device communicates with the UPF network element through the N3 interface (N3 for short); the SMF network element communicates with the UPF network element through the N4 interface (N4 for short); and the UPF network element accesses the data network (DN) through the N6 interface (N6 for short). Figure 3 In the architecture shown, N1, N2, N3, N4 and N6 represent reference points between relevant network elements / network functions.

[0113] also, Figure 3 The control plane functions of the AUSF, AMF, SMF, NSSF, NEF, NRF, PCF, UDM, UDR, CHF, and AF network elements shown are interacted through service-oriented interfaces. For example, the service-oriented interface provided by the AUSF network element is Nausf; that of the AMF network element is Namf; that of the SMF network element is Nsmf; that of the NSSF network element is Nnssf; that of the NEF network element is Nnef; that of the NRF network element is Nnrf; that of the PCF network element is Npcf; that of the UDM network element is Nudm; that of the UDR network element is Nudr; that of the CHF network element is Nchf; and that of the AF network element is Naf. For relevant functional and interface descriptions, please refer to the 5G system architecture diagram in the 23501 standard, which will not be elaborated here.

[0114] It should be understood that the names of the aforementioned core network devices, such as MME and AMF, are merely names and do not constitute a limitation on the devices themselves. It is understood that other names may be used in 5G networks and other future networks, and this application embodiment does not specifically limit this. For example, an AMF network element may also be called AMF or an AMF entity; this will be uniformly explained here and will not be repeated below.

[0115] Optionally, the core network equipment can be implemented by a single device, multiple devices working together, or it can be a functional module within a single device. This application does not specifically limit this. It is understood that the aforementioned functional module can be a network element in a hardware device, a software functional module running on dedicated hardware, or a virtualized functional module instantiated on a platform (e.g., a cloud platform).

[0116] To facilitate understanding of the embodiments of this application, the terminology used in the embodiments of this application will be briefly explained below. It should be understood that these explanations are only for the purpose of understanding the embodiments of this application and should not constitute any limitation on this application.

[0117] 1. Visited network operator

[0118] A visited network refers to an operator that provides inter-network roaming services to terminal equipment of other operators within the roaming area. The network providing inter-network roaming services to terminal equipment of other operators is described as a visited network. For example, inter-network roaming services can be 5G core network inter-network roaming services.

[0119] 2. Home network operator

[0120] The home network operator refers to the operator that provides inter-network roaming services to the terminal devices of this network through other operator networks within the roaming area. The network that provides inter-network roaming services to the terminal devices of this network through other operator networks is described as the home network. For example, inter-network roaming services can be 5G core network inter-network roaming services.

[0121] 3. Cross-network roaming

[0122] Inter-network roaming refers to the ability of a terminal device to access services provided by its home network through a visited network. The operator of the visited network is different from the operator of the terminal device's home network, but they belong to the same country. Inter-network roaming can also be referred to as national roaming. This application embodiment only uses inter-network roaming as an example for description.

[0123] For inter-network roaming, both operators construct and manage their access networks and core networks independently, and mobile users are managed independently. The two operators providing inter-network roaming services provide corresponding services to roaming terminal devices based on inter-network roaming protocols. Inter-network roaming is implemented using home routing, meaning that roaming user data returns to the home network, and services are provided to the terminal devices from the home network.

[0124] For example, in a 5G SA scenario, a terminal device in a roaming area cannot access its home network and instead uses 5G services, such as data services, IMS-based voice / video services, and SMS services, by accessing a visited network. In this case, inter-network roaming can also be described as 5G core network inter-network roaming or 5G core network roaming. In this application embodiment, only 5G core network inter-network roaming is described as an example.

[0125] 4. Wander out of the scene, wander back to the scene

[0126] Roaming out refers to a scenario where a terminal device enters a roaming area, accesses the visited network, connects to the home network via a roaming interoperability interface, and then receives services from the home network. For example, the visited network could be the visited operator's 5G network, and the home network could be the home operator's 5G network. Figure 4 As shown, in 5G standalone networking, the visited network and the home network are connected via a boarder gateway (BG). An example of the connection between network elements in the visited network and network elements in the home network is as follows: Figure 5 As shown.

[0127] In addition, the visited operator's 4G network does not provide 5G core network inter-network roaming services and does not support voice fallback to the visited operator's 4G network.

[0128] The roaming scenario refers to when a terminal device leaves the roaming area and, upon finding a signal from its home network, connects to that network.

[0129] As one possible implementation, the terminal device is configured with a Subscriber Identity Module (SIM) card. The SIM card serves as the identifier of the mobile user's network identity. The SIM card is used to store user data and complete user authentication. One SIM card corresponds to one mobile user. It should be noted that the SIM card can store a user identifier. For example, the user identifier can be an International Mobile Subscriber Identification Number (IMSI) or a Subscription Permanent Identifier (SUPI). The SIM card can be implemented as a physical card, such as a standard SIM card, Mini-SIM card, Micro SIM card, or Nano SIM card. This type of SIM card is also called a Universal Subscriber Identity Module (USIM) card. The SIM card can also be implemented as a built-in chip, such as an embedded-SIM (eSIM) card. The SIM card can also be implemented in software, but this embodiment does not limit the implementation in this application.

[0130] The SIM card stores the identity (ID) of the home operator's PLMN. When powered on, the terminal device prioritizes selecting the home operator's PLMN for camping and service execution. The terminal device receives system broadcast messages from the access network equipment. These system broadcast messages include the PLMN ID. When selecting a network, the terminal device determines the operator by parsing the PLMN ID from the system broadcast message and prioritizes selecting the home operator's PLMN for camping.

[0131] After the terminal device camps on the home operator's PLMN, it sends a registration request message to the home operator's core network equipment. The core network equipment then sends Equivalent Public Land Mobile Network (EPLMN) information to the terminal device. The EPLMN information includes one or more PLMN IDs. The PLMN ID in the EPLMN information can be the PLMN ID of the visited network operator. The terminal device stores the received EPLMN information and treats the PLMN contained in the EPLMN information as equivalent to the home operator's PLMN during subsequent network selection, assuming they have the same network selection priority. For example, when the terminal device moves to the coverage area of ​​the visited network, it obtains the visited network operator's PLMN ID by parsing the system broadcast message from the access network equipment. If the terminal device determines that the PLMN ID matches the one obtained in the registration acceptance message, it camps on the visited network operator's base station and initiates a registration request to the visited network operator's core network equipment, thereby accessing the visited network.

[0132] For terminal devices, there are two ways to perform voice services in 5G standalone networking:

[0133] Method 1, Voice over New Radio (VoNR)

[0134] VoNR refers to establishing a voice transmission channel in an NR network to achieve VoNR functionality.

[0135] Method 2: Evolved Packet System (EPS) fallback

[0136] Method 2 cannot establish a voice transmission channel through the NR network. The terminal device needs to fall back to the 4G network and establish a voice transmission channel through the 4G network to perform voice services. In this case, the AMF network element of the 5G core network needs to open an interface with the MME network element of the 4G core network.

[0137] It should be noted that both Method 1 and Method 2 are based on IMS to implement voice services.

[0138] In the initial stages of 5G SA network deployment, operators' networks do not support VoNR. Consequently, existing 5G SA-enabled terminal devices do not support VoNR and rely on EPS fallback functionality for voice services.

[0139] However, in 5G core network roaming scenarios, the interface between the visited network and the home network's AMF network elements is open, but the interface between the visited network's AMF network elements and the home network's MME network elements is not open. Therefore, terminal devices cannot use EPS fallback for voice services, causing users to be unable to answer calls and impacting user experience.

[0140] In view of this, embodiments of this application provide two communication methods. The communication methods of this application (such as the first communication method or the second communication method) can be applied to... Figures 1 to 5 The communication system shown.

[0141] In the first communication method provided in this application embodiment, the terminal device sends first information to the core network device of its home network. The first information indicates that the terminal device supports VoNR or inter-network roaming. Alternatively, the first information requests the PLMN information of the visited network, where the operator of the visited network is different from the operator of the terminal device's home network. The terminal device then receives the PLMN information of the visited network from the core network device. In this way, the core network device only sends the PLMN information of the visited network to the terminal device if it determines that the terminal device supports VoNR or if the terminal device requests the PLMN information of the visited network. Even if the operator of the visited network is different from the operator of the home network, the terminal device can still access the visited network and perform voice services through the visited network, avoiding the problem of being unable to perform voice services after accessing the visited network due to the terminal device's lack of VoNR support.

[0142] like Figure 6 As shown, the first communication method 600 provided in this application embodiment includes the following steps:

[0143] S601. The terminal device sends first information to the core network device of its home network. Correspondingly, the core network device of the home network receives the first information from the terminal device.

[0144] For example, the core network device can be Figure 2 The MME shown can also be Figure 3 The AMF shown is an example. It should be understood that, with the evolution of communication technology, core network equipment may have other names, and the embodiments of this application do not limit this.

[0145] The first information has two possible implementation methods (i.e., Method 1 and Method 2 below), which are described in detail below:

[0146] In Method 1, the first piece of information indicates that the terminal device supports VoNR or inter-network roaming. For details on VoNR and inter-network roaming, please refer to the glossary section; they will not be elaborated upon here.

[0147] It should be noted that in this embodiment, if the terminal device supports inter-network roaming, then the terminal device also supports VoNR functionality. Since terminal devices that do not support VoNR cannot conduct voice services within the visited network, this type of terminal device cannot reside on the visited network and can only reside on the home network; therefore, we can consider this type of terminal device to not support inter-network roaming. Conversely, only terminal devices that support VoNR can reside on the visited network and conduct voice services via VoNR; therefore, we can consider this type of terminal device to support inter-network roaming. Therefore, supporting inter-network roaming and supporting VoNR can be considered equivalent.

[0148] For example, the first information can be a direct indication, indicating that the terminal device supports VoNR or inter-network roaming. Alternatively, the first information can also be an indirect indication, indicating that the terminal device supports VoNR or inter-network roaming. For example, Table 1a shows one possible mapping relationship.

[0149] Table 1a

[0150] character characteristic A1 Supports cross-network roaming A2 Support VoNR

[0151] In Table 1a, support for inter-network roaming corresponds to A1, and support for VoNR corresponds to A2. In some embodiments, if the first information includes A1, it can be understood that the first information is used to indicate that the terminal device supports inter-network roaming. If the first information includes A2, it can be understood that the first information is used to indicate that the terminal device supports VoNR.

[0152] It should be understood that the first information can also be indicated in other forms, and this application embodiment does not limit this. The above description only takes the terminal device supporting VoNR or inter-network roaming as an example. Conversely, if the terminal device does not support VoNR and inter-network roaming, the first information can also provide corresponding indications. For example, if the terminal device does not support inter-network roaming, the first information indicates that the terminal device does not support inter-network roaming. Similarly, if the terminal device does not support VoNR, the first information indicates that the terminal device does not support VoNR. Likewise, the first information can be a direct indication, indicating that the terminal device does not support VoNR or inter-network roaming. Alternatively, the first information can also be an indirect indication, indicating that the terminal device does not support VoNR or inter-network roaming. For example, Table 1b shows a possible mapping relationship.

[0153] Table 1b

[0154] character characteristic B1 Cross-network roaming is not supported. B2 VoNR is not supported.

[0155] In Table 1b, "Does not support inter-network roaming" corresponds to B1, and "Does not support VoNR" corresponds to B2. In some embodiments, if the first information includes B1, it can be understood that the first information is used to indicate that the terminal device does not support inter-network roaming. If the first information includes B2, it can be understood that the first information is used to indicate that the terminal device does not support VoNR.

[0156] Method 2: The first piece of information is used to request the PLMN information of the visited network. The operator of the visited network is different from the operator of the terminal device's home network. For example, the PLMN information includes the PLMN ID.

[0157] For example, the first information can directly indicate a request to obtain the PLMN information of the visited network, or it can indirectly indicate a request to obtain the PLMN information of the visited network, such as by using 1 bit. For example, a value of 1 indicates a request to obtain the PLMN information of the visited network. Correspondingly, a value of 0 indicates that it is not necessary to obtain the PLMN information of the visited network. Or, conversely, a value of 0 indicates a request to obtain the PLMN information of the visited network, and a value of 1 indicates that it is not necessary to obtain the PLMN information of the visited network. Alternatively, if the first information is sent, it indicates a request to obtain the PLMN information of the visited network. If the first information is not sent, it indicates that it is not necessary to obtain the PLMN information of the visited network. This embodiment of the application does not limit this.

[0158] It should be noted that, in the embodiments of this application, the terminal device sending the first information to the core network device means that the terminal device sends the first information to the access network device, and the access network device then sends the first information to the core network device. Since the access network device plays a transparent transmission role in this step, for the sake of brevity, it is directly described in the embodiments and accompanying drawings as the terminal device sending the first information to the core network device.

[0159] Optional, combined Figure 2 or Figure 3 The transmission process of the first information is described exemplarily as follows:

[0160] by Figure 2 For example, in the implementation of core network equipment as Figure 2 In the case of MME, as a possible implementation method, such as Figure 7a As shown, S601 can be implemented as S601a:

[0161] S601a, the terminal device sends first information to the MME of the home network via an attach request message. Correspondingly, the MME of the home network receives the first information from the terminal device via an attach request message.

[0162] In other words, the attach request message carries first information. Thus, during the 4G registration process, the terminal device can send this first information to the MME, enabling the MME to know that the terminal device supports VoNR, or for the terminal device to request the PLMN information of the visited network, preventing the MME from sending the PLMN information of the visited network to terminal devices that do not support VoNR.

[0163] Optionally, the first information can be carried in a field indicating the network capabilities of the user equipment in the attach request message. For example, the first information can be carried in a field indicating the 4G network capabilities of the user equipment, such as the UE network capability field, or it can be carried in a field indicating the 5G network capabilities of the user equipment, such as the N1 interface UE network capability field. Here, the N1 interface is the interface through which the terminal equipment communicates with the AMF network element; for details, please refer to [link to relevant documentation]. Figure 3 The details of the description will not be repeated here. It should be understood that the first information can also be carried in other fields in the attach request message, and this application embodiment does not limit this.

[0164] For example, a field indicating the network capabilities of a user equipment (such as UE network capability or N1 UE network capability field) can carry first information through a certain number of preset bits. These preset bits may include bits that are fixed bits in the field indicating the user equipment's network capabilities, such as bits that were originally in a spare state.

[0165] See Table 2, which shows one possible UE network capability field. The bits that can carry initial information in the UE network capability field are indicated by circles.

[0166] Table 2

[0167]

[0168] As shown in Table 2, byte 1 indicates the information element identifier (IEI), i.e., the UE network capability IEI. Byte 2 indicates the length of the UE network capability contents. Byte 3 carries information about the Evolved Packet System (EPS) encryption algorithm, byte 4 carries information about the EPS integrity algorithm, byte 5 carries information about the Universal Mobile Telecommunications System (UMTS) encryption algorithm, and byte 6 carries information about the UMTS integrity algorithm and the Universal Multiple-Octet Coded Character Set (UCS). Bytes 7 to 10 (e.g., bits 1 to 5 of byte 10) may include information about features 1 to 29. Features 1 to 29 can be found in related technical descriptions and will not be repeated here. Bytes 10 (e.g., bits 6, 7, and 8 of byte 10) to 15 include bits in a spare state. In this case, the fixed bit includes at least one of the following bits: a portion of the bits in byte 10 (such as bits 6, 7 and 8 in byte 10), and all the bits in bytes 11, 12, 13, 14 and 15.

[0169] See Table 3, which shows one possible N1 UE network capability field. The bits that can carry the first information in the N1 UE network capability field are shown in circles.

[0170] Table 3

[0171]

[0172] As shown in Table 3, byte 1 indicates the IEI, i.e., the N1 UE network capability IEI. Byte 2 indicates the length of the N1 UE network capability contents. Bits 1 to 6 of byte 3 may include information on features 1 to 5. Features 1 to 5 can be found in related technical descriptions and will not be repeated here. Bytes 3 (such as bits 7 and 8 of byte 3) and byte 4 include bits in a standby state. In this case, the fixed bit includes at least one of the following bits: some bits in byte 3 (such as bits 7 and 8 of byte 3) and all bits in byte 4.

[0173] In Tables 2 and 3, for a bit indicated by a circle, a value of 0 indicates that it carries the first information, and a value of 1 indicates that it does not carry the first information. Alternatively, the opposite is true: a value of 1 indicates that it carries the first information, and a value of 0 indicates that it does not carry the first information. This application does not limit this.

[0174] Again Figure 2 For example, in the implementation of core network equipment as Figure 2 In the case of MME, as another possible implementation, such as Figure 7b As shown, S601 can be implemented as S601b:

[0175] S601b: The terminal device sends first information to the MME of the home network via a tracking area update (TAU) request message. Correspondingly, the MME of the home network receives the first information from the terminal device via a TAU request message.

[0176] In other words, the TAU request message carries first information. Thus, during the TAU process, the terminal device can send this first information to the MME, enabling the MME to know that the terminal device supports VoNR, or that the terminal device is requesting PLMN information for the visited network, thereby preventing the MME from sending PLMN information to terminal devices that do not support VoNR.

[0177] For example, mobile networks use tracking areas (TAs) to determine the location of terminal devices for location management and paging. Specifically, the core network equipment configures a tracking area list (TA list) for each terminal device. Typically, a TA list contains one or more tracking area codes (TACs), with each TAC identifying a TA. A TA can contain one or more cells. Subsequently, if the terminal device moves within the cells indicated by the configured TA list, a TAU (Transactional Access Usage) is not required. Correspondingly, when a service arrives for the terminal device, the core network equipment paging the terminal device within the area corresponding to the configured TA list. Conversely, if the terminal device moves out of the cells indicated by the TA list, the core network equipment does not know the terminal device's latest location, and the terminal device must perform a TAU, sending a TAU request message to the core network equipment. This allows the core network equipment to know the current TA the terminal device is in, and thus update the terminal device's TA list.

[0178] Optionally, the first information may be carried in a spare field or other field in the TAU request message, and this application embodiment does not limit this.

[0179] by Figure 3 For example, in the implementation of core network equipment as Figure 3 In the case of AMF, as a possible implementation, such as Figure 7c As shown, S601 can be implemented as S601c:

[0180] S601c: The terminal device sends first information to the AMF of its home network via a registration request message. Correspondingly, the AMF of the home network receives the first information from the terminal device via the registration request message.

[0181] In other words, the registration request message carries initial information. Thus, during the 5G registration process, the terminal device can send this initial information to the AMF (Application Management Provider), allowing the AMF to know that the terminal device supports VoNR, or that the terminal device is requesting PLMN information for the visited network, preventing the AMF from sending PLMN information to terminal devices that do not support VoNR.

[0182] Optionally, the first information can also be carried in a field indicating the network capabilities of the terminal device in the registration request message. For example, the first information can be carried in a field indicating the 4G network capabilities of the terminal device, such as the user equipment network capability (S1UE network capability) of the S1 interface. Here, the S1 interface is the interface between the eNB and the core network equipment in the E-UTRAN device. The S1 interface includes the S1-MME interface and the S1-U interface, such as... Figure 2 As shown, the S1-MME interface is the control plane interface, which is the interface for communication between the E-UTRAN device and the MME; the S1-U interface is the user plane interface, which is the interface for communication between the E-UTRAN device and the SGW. The first information can also be carried in fields indicating the 5G network capabilities of the terminal device, such as a mobility management capability field, specifically including 5G mobility management (5GMM) capability. It should be understood that the first information can also be carried in other fields in the registration request message, and this embodiment does not limit this.

[0183] For example, the fields indicating the network capabilities of the terminal device (such as the S1 UE network capability or 5GMM capability field) can carry first information through a certain number of preset bits. These preset bits may include bits in fixed positions within the fields indicating the user equipment's network capabilities, such as bits originally in a spare state.

[0184] See Table 4, which shows one possible 5GMM capability field. The bits that can carry the first information in the 5GMM capability field are indicated by circles.

[0185] Table 4

[0186]

[0187] As shown in Table 4, byte 1 indicates the IEI, i.e., the 5GMM capability IEI. Byte 2 indicates the length of the 5GMM capability contents. Bytes 3 to 6 (such as bits 1 to 3 in byte 6) may include information on features 1 to 27. Features 1 to 27 can be found in related technical descriptions and will not be repeated here. Bytes 6 (such as bits 4 to 8 in byte 6) to 15 include bits in a spare state. In this case, the fixed bit includes at least one of the following bits: some bits in byte 6 (such as bits 4 to 8 in byte 6), and all bits in bytes 7, 8, 9, 10, 11, 12, 13, 14, and 15. In Table 4, for a bit indicated by a circle, a value of 0 indicates that it carries the first information, and a value of 1 indicates that it does not carry the first information. Alternatively, conversely, when the bit is 1, it indicates that the first information is carried; when the bit is 0, it indicates that the first information is not carried. This application does not limit this.

[0188] Again Figure 3 For example, in the implementation of core network equipment as Figure 3 In the case of AMF, as another possible implementation, such as Figure 7d As shown, S601 can be implemented as S601d:

[0189] S601d: The terminal device sends the first information to the AMF via a Security Mode Complete (SMC) message. Correspondingly, the AMF receives the first information from the terminal device via a Security Mode Complete (SMC) message.

[0190] In other words, the secure mode completion message carries the initial information. This secure mode completion message is protected by an encryption key, thereby reducing the possibility of the initial information being tampered with or leaked, and improving the reliability of information transmission.

[0191] Optionally, the first information can also be carried in a field in the security mode completion message that indicates the network capabilities of the terminal device. For example, the first information can be carried in a field that indicates the 5G network capabilities of the terminal device, such as a mobility management capability field, specifically including a 5GMM capability field, as described in Table 4, which will not be repeated here. It should be understood that the first information can also be carried in other fields in the security mode completion message, and this embodiment of the application does not limit this.

[0192] For example, in Figure 7dBefore executing S601d, the terminal device first sends a registration request message to the AMF. Correspondingly, the AMF receives the registration request message from the terminal device.

[0193] The registration request message carries a subscriber concealed identifier (SUCI). The SUCI is generated by the terminal device. The SUCI includes at least one of the following information:

[0194] The first item, Subscription Permanent Identifier (SUPI Type), can have seven values, used to identify the seven types of encrypted SUPIs in the SUCI. For example, when the SUPI Type value is 0, it indicates that the SUPI is an International Mobile Subscriber Identification Number (IMSI). The IMSI is an identifier that distinguishes terminal devices. The IMSI includes the Mobile Country Code (MCC), Mobile Network Code (MNC), and Mobile Subscriber Identification Number (MSIN). The MCC uniquely identifies the country to which the mobile user belongs; for example, my country's MCC is 460. The MNC identifies which operator the mobile user belongs to. The MSIN identifies the mobile user within a specific mobile communication network. When the SUPI Type value is 1, it indicates that the SUPI is a Network Specific Identifier.

[0195] The second item is the home network identifier. For example, when the SUPI Type indicates that the SUPI is IMSI, the home network identifier may include the MCC and MNC. The MCC and MNC, combined, uniquely identify the network operator of the terminal device.

[0196] It should be understood that the above two pieces of information are merely illustrative examples, and SUCI may also include other information, which will not be elaborated here.

[0197] It should be noted that, compared to the registration request message of S601c, the registration request message carrying SUCI does not carry the aforementioned first information.

[0198] After receiving the registration request message carrying the SUCI, the AMF authenticates the terminal device based on the SUCI. Then, the AMF sends a security mode command message to the terminal device. Correspondingly, the terminal device receives the security mode command message from the AMF.

[0199] The secure mode command message carries information about the encryption key, such as the key used for negotiation between the AMF and the terminal device. The encryption key carried in the secure mode command message is used to protect the secure mode completion message; see the description of S601d for details, which will not be repeated here.

[0200] It should be understood that, Figures 7a to 7d The above is merely an example illustrating which messages can be used to send the first information. Of course, the first information can also be sent using other messages, and this application does not limit this.

[0201] S602. The core network equipment sends the PLMN information of the visited network to the terminal equipment. Correspondingly, the terminal equipment receives the PLMN information of the visited network from the core network equipment.

[0202] The PLMN information in S602 is the same as that in S601, and will not be described again here.

[0203] For example, if operator A's PLMN ID for inter-network roaming in region X is 46030, then a VoNR-enabled terminal device of operator B will receive 46030 from the core network equipment when registering with operator B. The terminal device receiving 46030 can then select operator A's network and register with it. Conversely, a terminal device that does not support VoNR will not receive 46030 from the core network equipment and therefore cannot register with operator A's network.

[0204] Optional, combined Figure 2 or Figure 3 The following is an example of the transmission process of PLMN information in a visited network:

[0205] by Figure 2 As shown, the core network equipment is implemented as Figure 2 In the case of MME, as a possible implementation method, such as Figure 7a As shown, S602 can be implemented as S602a:

[0206] S602a: The MME sends the PLMN information of the visited network to the terminal device via an attach accept message. Correspondingly, the terminal device receives the PLMN information of the visited network from the MME via an attach accept message.

[0207] In other words, the registration and acceptance message carries the PLMN information of the visited network. For details on the specific implementation process of sending the PLMN information of the visited network via the registration and acceptance message, please refer to the introduction on sending EPLMN via the registration and acceptance message; it will not be repeated here.

[0208] Again Figure 2 As shown, the core network equipment is implemented as Figure 2 In the case of MME, as another possible implementation, such as Figure 7b As shown, S602 can be implemented as S602b:

[0209] S602b: The MME sends the PLMN information of the visited network to the terminal device via the TAU (Transaction Acceptance Unit). Correspondingly, the terminal device receives the PLMN information of the visited network from the MME via the TAU.

[0210] In other words, the TAU receives messages carrying the PLMN information of the visited network. Thus, if the terminal device supports VoNR, or if the terminal device requests to obtain the PLMN information of the visited network, the terminal device can obtain the PLMN information of the visited network during the TAU process, enabling the terminal device to perform voice services through the visited network.

[0211] by Figure 3 For example, in the implementation of core network equipment as Figure 3 In the case of AMF, as a possible implementation, such as Figure 7c and Figure 7d As shown, S602 can be implemented as S602c:

[0212] S602c and AMF send the PLMN information of the visited network to the terminal device via a registration accept message. Correspondingly, the terminal device receives the PLMN information of the visited network from the AMF via a registration accept message.

[0213] In other words, the registration and acceptance message carries the PLMN information of the visited network. For details on the specific implementation process of sending the PLMN information of the visited network via the registration and acceptance message, please refer to the introduction on sending EPLMN via the registration and acceptance message; it will not be repeated here.

[0214] It should be understood that, Figures 7a to 7d This document merely illustrates, by way of which messages are used to send PLMN information for a visited network. Of course, other messages can also be used to send PLMN information for a visited network, and this application does not limit this.

[0215] Thus, the terminal device sends first information to the core network device to enable the core network device to determine that the terminal device supports VoNR, or requests the PLMN information of the visited network from the core network device. Only in this case will the core network device send the PLMN information of the visited network to the terminal device. Even if the operator of the visited network is different from the operator of the home network, the terminal device can still access the visited network and perform voice services through the visited network, avoiding the problem of not being able to perform voice services after accessing the visited network due to the terminal device's lack of VoNR support.

[0216] This application also provides a second communication method. In this second communication method, the core network device determines that the terminal device supports VoNR. The core network device is the core network device of the terminal device's home network. Then, the core network device sends PLMN information of the visited network to the terminal device. The operator of the visited network is different from the operator of the terminal device's home network. In this way, the core network device only sends the PLMN information of the visited network to the terminal device if it determines that the terminal device supports VoNR. Even if the operator of the visited network is different from the operator of the home network, the terminal device can still access the visited network and perform voice services through the visited network, avoiding the problem that the terminal device cannot perform voice services after accessing the visited network because it does not support VoNR.

[0217] like Figure 8 As shown, the second communication method 800 provided in this application embodiment includes the following steps:

[0218] S801, The core network equipment determines that the terminal equipment supports VoNR.

[0219] Among them, core network equipment refers to the core network equipment in the home network of the terminal equipment. For example, core network equipment can be... Figure 2 The MME shown can also be Figure 3 The AMF shown is an example. It should be understood that, with the evolution of communication technology, core network equipment may have other names, and the embodiments of this application do not limit this.

[0220] For an explanation of VoNR, please refer to the glossary section; it will not be repeated here.

[0221] Optionally, the implementation process of S801 includes the following two examples (Example 1 and Example 2):

[0222] like Figure 9 As shown in the dashed box containing "Example 1", S801 is implemented as S801a and S801b:

[0223] S801a: The access network device sends radio capability information to the core network device. Correspondingly, the core network device receives the radio capability information from the access network device.

[0224] The radio capability information indicates the radio capabilities of the terminal device. For example, the radio capability information may include UE radio capability info. This information may include IMS parameters, where the IMS-ParametersFRX-Diff field may include a VoNR field with a value of "supported," indicating that the terminal device supports VoNR. Alternatively, the IMS-ParametersFRX-Diff field may not include a VoNR field, or the VoNR field may have a value indicating "not supported," indicating that the terminal device does not support VoNR.

[0225] As one possible implementation, see Figure 10a , Figure 10a A schematic diagram of a process for transmitting wireless capability information is shown, and the specific steps are as follows:

[0226] Step 11: The terminal device sends a registration request message to the core network device. Correspondingly, the core network device receives the registration request message from the terminal device.

[0227] The registration request message is used to initiate registration.

[0228] For example, in the core network equipment implemented as Figure 2 In the context of MME (Mobile Equipment Management), the registration request message is used for terminal devices to register with the 4G network. The registration request message can also be described as an attach request, such as... Figure 10b As shown. Implemented in core network equipment as Figure 3 In the case of AMF (Advanced Mobile Network Configuration), the registration request message is used for terminal devices to register with the 5G network. The registration request message can also be referred to as a registration equestrian message, such as... Figure 10c As shown.

[0229] Step 12: The core network device sends a capability matching request message to the access network device. Correspondingly, the access network device receives the capability matching request message from the core network device.

[0230] Among them, the capability matching request message is used to request the access network device to determine whether the terminal device supports IMS voice.

[0231] For example, in the core network equipment implemented as Figure 2In the case of an MME, the access network device can be an eNB, and the capability matching request can also be described as a UE capability matching request for the application protocol (AP) of the S1 interface, such as denoted as S1-AP UE Capability match request. Figure 10b As shown. Implemented in core network equipment as Figure 3 In the case of AMF (Access Module), the access network device can be a gNB (Gateway Node), and the capability matching request can also be described as a UE capability matching request for the N2 interface, such as denoted as N2 UE Capability match request. Figure 10c As shown.

[0232] Step 13: The access network device sends a capability query message to the terminal device. Correspondingly, the terminal device receives the capability query message from the access network device.

[0233] Among them, the capability query message is used to query the wireless capabilities of the terminal device.

[0234] For example, in the core network equipment implemented as Figure 2 MME, or Figure 3 In the case of AMF, the capability query message may include the user equipment capability query message, i.e., UE Capability enquiry.

[0235] Step 14: The terminal device sends capability information to the access network device. Correspondingly, the access network device receives the capability information from the terminal device.

[0236] Among them, capability information indicates the wireless capabilities of the terminal device.

[0237] For example, in the core network equipment implemented as Figure 2 MME, or Figure 3 In the case of AMF, capability information can be recorded as UE capability information.

[0238] Step 15: The access network device sends a capability matching response message to the core network device. Correspondingly, the core network device receives the capability matching response message from the access network device.

[0239] Among them, the capability matching response message at least indicates whether the terminal device supports IMS voice.

[0240] For example, in the core network equipment implemented as Figure 2 MME, or Figure 3In the case of AMF, the capability matching response message can also be described as the UE radio capability match response.

[0241] Since VoNR is based on IMS voice, when the capability matching response message indicates that the terminal device supports IMS voice, the core network device waits to receive radio capability information. That is, the core network device first executes S801a and then S801b. The radio capability information in S801a can be determined based on the capability information in step 14, or the radio capability information in S801a can include the capability information in step 14. This embodiment does not limit this.

[0242] As another possible implementation, see Figure 11 , Figure 11 A schematic diagram of a process for transmitting wireless capability information is shown, and the specific steps are as follows:

[0243] Step 21: The terminal device sends a registration request message to the core network device. Correspondingly, the core network device receives the registration request message from the terminal device.

[0244] Step 21 can be found in the description of step 11, and will not be repeated here.

[0245] Step 22: When the core network device has not saved the radio capability information, the core network device sends an initial context setup request to the access network device. Correspondingly, the access network device receives the initial context setup request from the core network device.

[0246] The initial context establishment request does not carry wireless capability information. Wireless capability information indicates the wireless capabilities of the terminal device; see the description of S801a for details, which will not be repeated here. For example, the initial context establishment request may carry security context information, but this embodiment does not limit this aspect.

[0247] In this case, the access network device learns that the core network device has not saved the terminal device's radio capability information. Then, the access network device executes steps 23, 24, and S801a:

[0248] Step 23: The access network device sends a capability query message to the terminal device. Correspondingly, the terminal device receives the capability query message from the access network device.

[0249] Step 23 can be found in the description of step 13, and will not be repeated here.

[0250] Step 24: The terminal device sends capability information to the access network device. Correspondingly, the access network device receives the capability information from the terminal device.

[0251] Step 24 can be found in the description of step 14, and will not be repeated here.

[0252] For the access network device, after executing step 24, S801a is executed. The radio capability information in S801a can be determined based on the capability information in step 24, or the radio capability information in S801a can include the capability information in step 24; this embodiment does not limit this. For the core network device, the core network device executes S801a first, then executes S801b.

[0253] It should be understood that, Figure 11 In the flowchart shown, the core network equipment can be implemented as follows: Figure 2 In the case of an MME, the access network device can be an eNB, such as... Figure 10b As shown. Core network equipment can also be implemented as Figure 3 In the case of AMF, the access network device can be a gNB, such as... Figure 10c As shown, it will not be elaborated further here.

[0254] S801b and core network equipment determine whether the terminal equipment supports VoNR based on radio capability information.

[0255] For example, taking radio capability information including IMS parameters as an example, when the IMS-ParametersFRX-Diff field of the parameter includes a VoNR field with a value of "supported", the core network device determines that the terminal device supports VoNR.

[0256] It should be understood that, taking the radio capability information including the IMS-ParametersFRX-Diff field as an example, when the IMS-ParametersFRX-Diff field does not include the VoNR field, or when the value of the VoNR field indicates that it is not supported, the core network equipment determines that the terminal equipment does not support VoNR.

[0257] Thus, through Figure 9 The S801a and S801b shown in the dashed box of "Example 1" allow the core network equipment to independently determine whether the terminal device supports VoNR based on the radio capability information.

[0258] like Figure 9 As shown in the dashed box containing "Example 2", the S801 is implemented as S801c and S801d:

[0259] S801c: The access network device sends indication information to the core network device. Correspondingly, the core network device receives the indication information from the access network device.

[0260] The indication information indicates that the terminal device supports VoNR. For details, please refer to the introduction of S601, which will not be repeated here.

[0261] For example, the characteristics indicated by the indication information are determined based on the terminal device's capability information. Taking the IMS parameter in the capability information as an example, when the IMS-ParametersFRX-Diff field of this parameter includes a VoNR field with a value of "supported," the access network device determines that the terminal device supports VoNR. Accordingly, the indication information indicates that the terminal device supports VoNR. When the IMS-ParametersFRX-Diff field does not include a VoNR field, or when the value of the VoNR field indicates "not supported," the access network device determines that the terminal device does not support VoNR. Accordingly, the indication information indicates that the terminal device does not support VoNR.

[0262] Optional, such as Figure 12a As shown, S801c can be replaced by the following steps: The access network device sends an indication message to the core network device via a radio capability matching response message. Correspondingly, the core network device receives the indication message from the access network device via a radio capability matching response message.

[0263] For example, the wireless capability matching response message carries indication information through a preset number of spare fields.

[0264] In other words, the wireless capability matching response message carries the aforementioned indication information, thereby enabling the core network equipment to obtain the aforementioned indication information.

[0265] It should be understood that the above description uses the wireless capability matching response message as an example to illustrate the carrying of indication information. Of course, indication information can also be transmitted through other messages or carried in independent messages, and this application embodiment does not limit this.

[0266] It should be noted that access network devices can execute S801c independently, or they can execute S801c in response to requests from core network devices. In this case, such as Figure 12a As shown, the core network device executes S801e before executing S801c:

[0267] S801e: The core network device sends a first request message to the access network device. Correspondingly, the access network device receives the first request message from the core network device.

[0268] The first request message requests to obtain indication information. The indication information in S801e is the same as that in S801c, and will not be described again here.

[0269] Optionally, S801e can be replaced by the following steps: The core network device sends a first request message to the access network device via a capability information indication message. Correspondingly, the access network device receives the first request message from the core network device via a capability information indication message.

[0270] For example, the capability information indication message carries the first request message through a preset number of spare fields.

[0271] For example, in combination Figure 2 or Figure 3 The transmission process of the first request message is described below: In the core network equipment implementation as... Figure 2 In the case of an MME, the access network device can be an eNB, and the capability information indication message can include the user equipment capability information indication (S1-AP UE capability info indication) of the application protocol of the S1 interface, such as... Figure 12b As shown. Implemented in core network equipment as Figure 3 In the case of AMF, the access network device can be a gNB, and the capability information indication message can include the N2 interface UE capability info indication, such as... Figure 12c As shown.

[0272] In other words, the capability information indication message carries the aforementioned first request message, thereby sending the aforementioned indication information to the access network device.

[0273] It should be understood that the above description uses a capability information indication message as an example to illustrate the carrying of the first request message. Of course, the first request message can also be transmitted through other messages or carried in an independent message, and this application embodiment does not limit this.

[0274] S801d and core network equipment determine that the terminal equipment supports VoNR based on the instruction information.

[0275] For example, if the indication information indicates that the terminal device supports VoNR, the core network device can determine that the terminal device supports VoNR.

[0276] It should be understood that if the indication information indicates that the terminal device does not support VoNR, the core network device can determine that the terminal device does not support VoNR.

[0277] Thus, through Figure 9The S801c and S801d shown in the dashed box of "Example 2" are used by the access network device to determine whether the terminal device supports the VoNR function, and then inform the core network device so that the core network device knows whether the terminal device supports the VoNR function.

[0278] For core network equipment, if it is determined that the terminal equipment supports VoNR, the core network equipment executes S802; otherwise, if it is determined that the terminal equipment does not support VoNR, the core network equipment does not execute S802.

[0279] S802. The core network equipment sends the PLMN information of the visited network to the terminal equipment. Correspondingly, the terminal equipment receives the PLMN information of the visited network from the core network equipment.

[0280] For details on S802, please refer to the description of S602; it will not be repeated here.

[0281] In other words, the core network equipment only sends the visited network's PLMN information to the terminal device after confirming that the terminal device supports VoNR functionality. Even if the operator of the visited network is different from the operator of the home network, the terminal device can still access the visited network and perform voice services through the visited network, avoiding the problem of being unable to perform voice services after accessing the visited network due to the terminal device's lack of VoNR support.

[0282] The above mainly describes the solutions provided by the embodiments of this application from the perspective of interaction between various network elements. Correspondingly, the embodiments of this application also provide a communication device, which can be a network element in the above method embodiments, a device containing the above network element, or a component that can be used in a network element. It is understood that, in order to achieve the above functions, the communication device includes hardware structures and / or software modules corresponding to the execution of each function. Those skilled in the art should readily recognize that, in conjunction with the units and algorithm steps of the various examples described in the embodiments disclosed herein, this application can be implemented in hardware or a combination of hardware and computer software. Whether a function is executed by hardware or by computer software driving hardware depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0283] For example, Figure 13 A schematic diagram of a communication device 1300 is shown. The communication device 1300 includes a processing unit 1301, a transmitting unit 1302, and a receiving unit 1303.

[0284] In one possible example, taking the communication device 1300 as a terminal device, the processing unit 1301 is used to support the terminal device in performing... Figure 6Other processing operations that the terminal device needs to perform. The sending unit 1302 is used to support the terminal device in performing these operations. Figure 6 In step S601, and / or other sending operations that the terminal device needs to perform in the embodiments of this application. The receiving unit 1303 is used to support the terminal device in performing... Figure 6 S602 in the example, and / or other receiving operations that the terminal device needs to perform in the embodiments of this application.

[0285] In another possible example, taking the communication device 1300 as a terminal device, the processing unit 1301 is used to support the terminal device in performing... Figure 8 Other processing operations that the terminal device needs to perform. The sending unit 1302 is used to support the terminal device in performing these operations. Figure 8 Other sending operations that the terminal device needs to perform. The receiving unit 1303 is used to support the terminal device in performing these operations. Figure 8 S802 in the example, and / or other receiving operations that the terminal device needs to perform in the embodiments of this application.

[0286] In one possible example, taking the communication device 1300 as a core network device, the processing unit 1301 is used to support the core network device in performing... Figure 6 Other processing operations that the core network equipment needs to perform. The sending unit 1302 is used to support the core network equipment in performing these operations. Figure 6 In step S602, and / or other transmission operations that the core network device needs to perform in the embodiments of this application. The receiving unit 1303 is used to support the core network device in performing... Figure 6 S601 in the example, and / or other receiving operations that the core network equipment needs to perform in the embodiments of this application.

[0287] In another possible example, taking communication device 1300 as a core network device, processing unit 1301 is used to support the core network device in performing... Figure 8 In step S801, and / or other processing operations that the core network device needs to perform in the embodiments of this application. The sending unit 1302 is used to support the core network device in performing... Figure 8 In step S802, and / or other transmission operations that the core network device needs to perform in the embodiments of this application. The receiving unit 1303 is used to support the core network device in performing... Figure 8 Other receiving operations that the core network equipment needs to perform.

[0288] Optionally, the communication device 1300 may also include a storage unit 1304 for storing the program code and data of the communication device, and the data may include, but is not limited to, raw data or intermediate data.

[0289] The processing unit 1301 may be a processor or controller, such as a CPU, a general-purpose processor, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. It can implement or execute the various exemplary logic blocks, modules, and circuits described in conjunction with the disclosure of this application. The processor may also be a combination that implements computational functions, such as a combination of one or more microprocessors, a combination of a DSP and a microprocessor, etc.

[0290] The transmitting unit 1302 may be a communication interface, a transmitter, or a transmitting circuit, etc. Here, the communication interface is a general term. In a specific implementation, the communication interface may include multiple interfaces, such as the interface between the terminal device and the core network device and / or other interfaces.

[0291] The receiving unit 1303 may be a communication interface, a receiver, or a receiving circuit, etc. The communication interface is a general term. In a specific implementation, the communication interface may include multiple interfaces, such as the interface between the terminal device and the core network device and / or other interfaces.

[0292] The transmitting unit 1302 and the receiving unit 1303 can be implemented as the same unit, either physically or logically.

[0293] Storage unit 1304 can be a memory.

[0294] When the processing unit 1301 is a processor, the sending unit 1302 and the receiving unit 1303 are communication interfaces, and the storage unit 1304 is a memory, the communication device involved in the embodiments of this application can be... Figure 14 As shown.

[0295] See Figure 14 As shown, the communication device includes a processor 1401, a communication interface 1402, and a memory 1403. Optionally, the communication device may also include a bus 1404. The communication interface 1402, processor 1401, and memory 1403 can be interconnected via the bus 1404; the bus 1404 can be a peripheral component interconnect (PCI) bus or an extended industry standard architecture (EISA) bus, etc. The bus 1404 can be divided into an address bus, a data bus, a control bus, etc. For ease of illustration, Figure 14The bus is represented by a single thick line, but this does not mean that there is only one bus or one type of bus.

[0296] Optionally, embodiments of this application also provide a computer program product carrying computer instructions, which, when executed on a computer, causes the computer to perform the methods described in the above embodiments.

[0297] Optionally, embodiments of this application also provide a computer-readable storage medium that stores computer instructions that, when executed on a computer, cause the computer to perform the methods described in the above embodiments.

[0298] Optionally, embodiments of this application also provide a chip, including: a processing circuit and a transceiver circuit, which are used to implement the methods described in the above embodiments. The processing circuit is used to perform processing actions in the corresponding method, and the transceiver circuit is used to perform receiving / transmitting actions in the corresponding method.

[0299] In the above embodiments, implementation can be achieved entirely or partially through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented entirely or partially in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available media can be magnetic media (e.g., floppy disks, hard disks, magnetic tapes), optical media (e.g., digital video discs (DVDs)), or semiconductor media (e.g., solid-state drives (SSDs)).

[0300] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of modules is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple modules or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces, indirect coupling or communication connection between devices or modules, and may be electrical or other forms.

[0301] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple devices. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0302] Through the above description of the embodiments, those skilled in the art can clearly understand that this application can be implemented by means of software plus necessary general-purpose hardware, and of course, it can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of this application, in essence, or the part that makes a contribution, can be embodied in the form of a software product. This computer software product is stored in a readable storage medium, such as a computer floppy disk, hard disk, or optical disk, and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments of this application.

[0303] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A communication method, characterized in that, include: The terminal device sends first information to the core network equipment of its home network, wherein the first information is used to instruct the terminal device to support Voice over New Radio (VoNR) or inter-network roaming, or the first information is used to request to obtain the Public Land Mobile Network (PLMN) information of the visited network, wherein the operator of the visited network is different from the operator of the terminal device's home network. The terminal device receives the PLMN information of the visited network from the core network device; the PLMN information of the visited network is sent by the core network device according to the first information and the first condition; the first condition includes: the interface between the core network device of the home network and the core network device of the visited network is not open; the core network device of the home network and the core network device of the visited network are core network devices of different communication standards.

2. The method according to claim 1, characterized in that, The terminal device sends the first information to the core network device of the home network via an attach request message.

3. The method according to claim 1, characterized in that, The terminal device sends the first information to the core network device of the home network via a registration request message.

4. The method according to claim 2 or 3, characterized in that, The first information is carried in a field indicating the network capabilities of the user equipment.

5. The method according to any one of claims 2, 3 or 4, characterized in that, The first information is carried in preset bits, wherein the preset bits include bits with fixed bits in a field indicating the network capabilities of the user equipment.

6. The method according to any one of claims 1, 2, 4 or 5, characterized in that, The first information is carried in one of the following: User equipment network capability field, or The user equipment network capability field of the N1 interface.

7. The method according to any one of claims 1, 3, 4 or 5, characterized in that, The first information is carried in one of the following: Mobile management capability field, or, The user equipment network capability field of the S1 interface.

8. The method according to claim 1, characterized in that, The terminal device sends the first information to the core network device of the home network through a secure mode.

9. The method according to claim 1, characterized in that, The terminal device sends the first information to the core network device of the home network via a Tracking Area Update (TAU) request message.

10. A registration method, characterized in that, include: The core network device receives first information from the terminal device, wherein the first information is used to instruct the terminal device to support Voice over New Radio (VoNR) or inter-network roaming, or the first information is used to request to obtain the Public Land Mobile Network (PLMN) information of the visited network, wherein the operator of the visited network is different from the operator of the terminal device's home network, and the core network device is the core network device of the terminal device's home network. The core network device sends the PLMN information of the visited network to the terminal device according to the first information and the first condition; the first condition includes: the interface between the core network device of the home network and the core network device of the visited network is not open; the core network device of the home network and the core network device of the visited network are core network devices of different communication standards.

11. The method according to claim 10, characterized in that, The core network device receives the first information from the terminal device via an attach request message.

12. The method according to claim 10, characterized in that, The core network device receives the first information from the terminal device via a registration request message.

13. The method according to claim 11 or 12, characterized in that, The first information is carried in a field indicating the network capabilities of the user equipment.

14. The method according to any one of claims 11, 12 or 13, characterized in that, The first information is carried in preset bits, which include bits with fixed bits in a field indicating the network capabilities of the user equipment.

15. The method according to any one of claims 10, 11, 13 or 14, characterized in that, The first information is carried in one of the following: User equipment network capability field, or The user equipment network capability field of the N1 interface.

16. The method according to any one of claims 10, 12, 13 or 14, characterized in that, The first information is carried in one of the following: Mobile management capability field, or, The user equipment network capability field of the S1 interface.

17. The method according to claim 10, characterized in that, The core network device receives the first information from the terminal device in a secure mode.

18. The method according to claim 10, characterized in that, The core network device receives the first information from the terminal device through a Tracking Area Update (TAU) request message.

19. A communication method, characterized in that, include: The core network equipment determines that the terminal equipment supports Voice over New Radio (VoNR), wherein the core network equipment is the core network equipment of the network to which the terminal equipment belongs; When the terminal device supports VoNR and meets the first condition, the core network device sends Public Land Mobile Network (PLMN) information of the visited network to the terminal device, wherein the operator of the visited network is different from the operator of the terminal device's home network; the first condition includes: the interface between the core network device of the home network and the core network device of the visited network is not open; the core network device of the home network and the core network device of the visited network are core network devices of different communication standards.

20. The method according to claim 19, characterized in that, The method further includes: The core network device receives radio capability information from the access network device, wherein the radio capability information indicates the radio capability of the terminal device; The core network equipment determines that the terminal equipment supports VoNR, including: The core network device determines that the terminal device supports VoNR based on the radio capability information.

21. The method according to claim 20, characterized in that, The method further includes: When the core network device does not save the radio capability information, the core network device sends an initial context establishment request to the access network device, wherein the initial context establishment request does not carry the radio capability information.

22. The method according to claim 19, characterized in that, The method further includes: The core network device receives indication information from the access network device, wherein the indication information indicates that the terminal device supports VoNR; The core network equipment determines that the terminal equipment supports VoNR, including: The core network equipment determines, based on the indication information, that the terminal equipment supports VoNR.

23. The method according to claim 22, characterized in that, The core network device receives the indication information from the access network device via a radio capability matching response message.

24. The method according to claim 22 or 23, characterized in that, The method further includes: The core network device sends a first request message to the access network device, wherein the first request message requests to obtain the indication information.

25. The method according to claim 24, characterized in that, The core network device sends the first request message to the access network device through the terminal device capability information indication message.

26. The method according to any one of claims 19 to 25, characterized in that, The core network device sends the PLMN information of the visited network to the terminal device by registering and receiving messages.

27. The method according to any one of claims 19 to 26, characterized in that, The core network equipment includes a mobility management entity (MME).

28. A communication device, characterized in that, It includes a unit for performing the method as described in any one of claims 1 to 9, or a unit for performing the method as described in any one of claims 10 to 18, or a unit for performing the method as described in any one of claims 19 to 27.

29. A communication device, characterized in that, The device includes a processor and an interface circuit. The interface circuit is used to receive signals from other communication devices besides the communication device and transmit them to the processor, or to send signals from the processor to other communication devices besides the communication device. The processor is used to implement the method as described in any one of claims 1 to 9, or to implement the method as described in any one of claims 10 to 18, or to implement the method as described in any one of claims 19 to 27, through logic circuits or execution code instructions.

30. A computer-readable storage medium, characterized in that, The storage medium stores a computer program or instructions that, when executed by a communication device, implement the method as described in any one of claims 1 to 9, or the method as described in any one of claims 10 to 18, or the method as described in any one of claims 19 to 27.

31. A communication system, characterized in that, include: Access network equipment and core network equipment; among which, The access network device is configured to send first information to the core network device, wherein the first information indicates the wireless capability of the terminal device, or the first information indicates that the terminal device supports Voice over New Radio (VoNR). The core network device is configured to receive the first information from the access network device, wherein the core network device is the core network device of the network to which the terminal device belongs; The core network equipment is further configured to determine, based on the first information, that the terminal device supports VoNR; The core network equipment is further configured to send Public Land Mobile Network (PLMN) information of the visited network to the terminal device when the terminal device supports VoNR and meets a first condition, wherein the operator of the visited network is different from the operator of the terminal device's home network; the first condition includes: the interface between the core network equipment of the home network and the core network equipment of the visited network is not open; and the core network equipment of the home network and the core network equipment of the visited network are core network equipment of different communication standards.

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