Communication method, communication system, and communication apparatus

Abstract

A communication method, a communication system, and a communication apparatus. The method comprises: a terminal device sends to a mobility management network element a message for registration of a CS voice service, and correspondingly, the mobility management network element receives the message for registration of the CS voice service; and when the CS voice service is unavailable, the mobility management network element sends a response message to the terminal device, wherein the response message is used for instructing the terminal device to camp on a first network, and the first network provides a data service for the terminal device.

Description

Communication method, communication system and communication device

[0001] This application claims priority to the Chinese patent application with application number 202410340345.5 filed with the State Intellectual Property Office of China on March 21, 2024, and priority to the Chinese patent application with the invention name “Communication Method, Communication System and Communication Device”, all contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of communication technology, and in particular to a communication method, a communication system, and a communication device. Background Art

[0003] The 4th generation mobile communication technology (4G) network can provide voice services to terminal devices based on circuit switching (CS) networks and Internet protocol (IP) multimedia subsystem (IMS) networks. For terminal devices accessing the 4G network, the terminal device can send a joint registration request and an IMS registration request on the 4G network. The joint registration request is used to request CS voice and data services, and the IMS registration request is used to register for IMS voice services.

[0004] However, when both CS voice services and IMS voice services are unavailable, the 4G network cannot provide voice services for the terminal device, and the terminal device cannot reside on the 4G network, which will cause the terminal device's data services to be unable to proceed normally. Summary of the Invention

[0005] The embodiments of the present application provide a communication method, a communication system, and a communication device, which can ensure that data services of terminal devices are carried out normally.

[0006] In a first aspect, an embodiment of the present application provides a communication method, the method comprising:

[0007] The mobility management network element receives a message from the terminal device for registering the CS voice service; when the CS voice service is unavailable, the mobility management network element sends a response message to the terminal device, the response message being used to instruct the terminal device to reside in the first network, and the first network provides data services for the terminal device.

[0008] In the embodiment of the present application, the mobility management network element is a network element in the first network for performing mobility management. The first network can provide circuit switched fallback (CSFB), and the first network can provide voice services to the terminal device based on CS voice. The response message is used to indicate to the terminal device that the CS voice service registration is successful, thereby instructing the terminal device to reside in the first network, so that the first network can provide data services to the terminal device, and can ensure that the data services of the terminal device are carried out normally.

[0009] In combination with the first aspect, in one possible implementation, the first network provides voice services based on CS voice or IMS, and the mobility management network element sends a response message to the terminal device when the CS voice service is unavailable, including: the mobility management network element sends a response message to the terminal device when the CS voice service is unavailable and the IMS voice service is unavailable.

[0010] In an embodiment of the present application, when both the CS voice service and the IMS voice service are unavailable, the first network cannot provide voice services for the terminal device. In order to prevent the terminal device from being unable to reside in the first network, the mobility management network element can send a response message to the terminal device to enable the terminal device to reside in the first network, thereby ensuring that the data service of the terminal device is carried out normally.

[0011] With reference to the first aspect, in a possible implementation manner, the method further includes: the mobility management network element receiving information from the session management network element indicating that the voice service of the IMS is unavailable.

[0012] In an embodiment of the present application, the mobility management network element may determine whether the voice service of the IMS is available based on the instruction of the session management network element, and if the voice service of the IMS is unavailable, send a response message to the terminal device so that the terminal device resides in the first network.

[0013] In combination with the first aspect, in one possible implementation, the information used to indicate that the voice service of the IMS is unavailable includes statistical information of signaling messages between the terminal device and the session border controller (SBC) in the IMS, and the statistical information is used to determine whether the voice service of the IMS is available.

[0014] In the embodiment of the present application, the signaling messages between the terminal device and the SBC include an IMS voice registration request message and an IMS voice call request message initiated by the terminal device, and a response message returned by the SBC. The mobility management network element can determine the success rate of the IMS voice registration request or IMS voice call request based on the statistical information, and determine whether the IMS voice service is available based on the success rate of the IMS voice registration request or IMS voice call request, thereby accurately determining whether the IMS voice service is available.

[0015] In combination with the first aspect, in a possible implementation, the method further includes: the session management network element receives statistical information from the user plane network element, the statistical information is statistical information of signaling messages between the terminal device and the SBC in the IMS, and the statistical information is used to determine whether the voice service of the IMS is available; the session management network element determines that the voice service of the IMS is unavailable based on the statistical information.

[0016] In an embodiment of the present application, the user plane network element is used to forward messages between the terminal device and the SBC. Therefore, the user plane network element can count the signaling messages between the terminal device and the SBC to obtain the statistical information. The session management network element can determine the success rate of the IMS voice call request or the IMS voice registration request based on the statistical information, and based on the success rate, it can more accurately determine whether the voice service of the IMS is available. If the session management network element determines that the voice service of the IMS is unavailable, it sends information indicating that the voice service of the IMS is unavailable to the mobility management network element, so that the mobility management network element can send a response message based on the information, thereby enabling the terminal device to reside in the first network.

[0017] In combination with the first aspect, in a possible implementation method, the above-mentioned statistical information is the success rate of voice registration requests or voice call requests corresponding to at least one SBC address, and the session management network element determines that the voice service of the IMS is unavailable based on the statistical information, including: when the success rate of voice registration requests or voice call requests corresponding to at least one SBC address is less than a first threshold, the session management network element determines that the voice service of the IMS is unavailable.

[0018] In an embodiment of the present application, the success rate of voice registration requests or voice call requests corresponding to an SBC address refers to the success rate of voice registration requests or voice call requests initiated based on the SBC address. The session management network element can determine whether there is an available SBC address among the at least one SBC address based on the success rate of voice registration requests or voice call requests corresponding to the at least one SBC address. If the success rate of voice registration requests or voice call requests corresponding to the at least one SBC address is less than a first threshold, it indicates that there is no available SBC address, and therefore the session management network element determines that the voice service of the IMS is unavailable.

[0019] Exemplarily, when the success rate of voice call requests or voice registration requests corresponding to the first SBC address is greater than the first threshold, it indicates that the first SBC address is available, and the session management network element can determine that the IMS voice service is available. The session management network element can also instruct the terminal device to re-register for IMS voice based on the first SBC address. The first SBC is one of the at least one SBC.

[0020] With reference to the first aspect, in a possible implementation, the response message includes information indicating that the voice service of the IMS is unavailable.

[0021] In an embodiment of the present application, the mobility management network element can indicate to the terminal device through a response message that the voice service of the IMS is unavailable. The terminal device can not initiate an IMS voice registration request or an IMS voice call request based on the information used to indicate that the voice service of the IMS is unavailable, thereby saving signaling overhead.

[0022] In combination with the first aspect, in a possible implementation, the method further includes: the mobility management network element receiving a message from the terminal device for registering the IMS voice service; and the mobility management network element sending a message to the terminal device for rejecting the registration of the IMS voice service.

[0023] In an embodiment of the present application, when the voice service of the IMS is unavailable, the mobility management network element may directly reject the IMS voice registration request after receiving the IMS voice registration request of the terminal device without sending the voice registration request to the IMS, thereby saving signaling overhead.

[0024] In combination with the first aspect, in a possible implementation manner, the method further includes: the mobility management network element determining that the CS voice service is unavailable based on a voice service registration success rate corresponding to a mobile switching center (MSC).

[0025] In this embodiment of the present application, a terminal device can initiate a CS voice registration request to a mobility management network element. After receiving the CS voice registration request from the terminal device, the mobility management network element sends a voice registration request to the MSC to register the terminal device for CS voice. Therefore, the mobility management network element can monitor the voice service registration success rate corresponding to the MSC and accurately determine whether the CS voice service is available based on the voice service success rate corresponding to the MSC.

[0026] In combination with the first aspect, in a possible implementation manner, the method further includes: the mobility management network element receiving a message for requesting network attachment from the terminal device; and the mobility management network element sending a message for accepting network attachment to the terminal device.

[0027] In an embodiment of the present application, after receiving the message for requesting network attachment, the mobility management network element may establish a default bearer for the terminal device, where the default bearer is used to carry the data service of the terminal device. After the default bearer is established, the mobility management network element replies to the terminal device with a message for receiving network attachment, thereby ensuring that the data service of the terminal device can be carried out normally when the CS voice service and the IMS voice service are unavailable.

[0028] In a second aspect, an embodiment of the present application provides a communication method, the method comprising:

[0029] The user plane network element obtains statistical information about signaling messages between the terminal device and the SBC in the IMS; the user plane network element sends the statistical information to the session management network element, and the statistical information is used to determine whether the voice service of the IMS is available.

[0030] In conjunction with the second aspect, in a possible implementation, the method further includes: the session management network element determining, based on statistical information, that the voice service of the IMS is unavailable; and the session management network element sending information indicating that the voice service of the IMS is unavailable to the mobility management network element.

[0031] In combination with the second aspect, in one possible implementation, the statistical information is the success rate of voice registration requests or voice call requests corresponding to at least one SBC address, and the session management network element determines that the voice service of the IMS is unavailable based on the statistical information, including: when the success rate of voice registration requests or voice call requests corresponding to at least one SBC address is less than a first threshold, the session management network element determines that the voice service of the IMS is unavailable.

[0032] In a third aspect, an embodiment of the present application provides a communication method, the method comprising:

[0033] The terminal device sends a message to the mobility management network element for registering a circuit-switched CS voice service; the terminal device receives a response message from the mobility management network element, where the response message indicates that the terminal device resides in the first network, the first network provides data services for the terminal device, and the response message includes information indicating that the IMS voice service is unavailable.

[0034] In conjunction with the third aspect, in a possible implementation, the method further includes: the terminal device sending a message for registering the IMS voice service to the mobility management network element; and the terminal device receiving a message from the mobility management network element for rejecting the registration of the IMS voice service.

[0035] In a fourth aspect, an embodiment of the present application provides a communication system, wherein the communication method includes:

[0036] The session management network element receives statistical information from the user plane network element. The statistical information is statistical information of signaling messages between the terminal device and the SBC in the IMS. The statistical information is used to determine whether the voice service of the IMS is available; the session management network element determines that the voice service of the IMS is unavailable based on the statistical information.

[0037] The session management network element sends information indicating that the voice service of the IMS is unavailable to the mobility management network element.

[0038] In combination with the fourth aspect, in one possible implementation method, the statistical information is the success rate of voice registration requests or voice call requests corresponding to at least one SBC address, and the session management network element determines that the voice service of the IMS is unavailable based on the statistical information, including: the session management network element determines that the voice service of the IMS is unavailable when the success rate of voice registration requests or voice call requests corresponding to at least one SBC address is less than a first threshold.

[0039] In a fifth aspect, an embodiment of the present application provides a communication system, the communication system comprising:

[0040] The session management network element is used to send information indicating that the voice service of the IMS is unavailable to the mobility management network element;

[0041] The mobility management network element is used to receive a message from a terminal device for registering a CS voice service, and when the CS voice service is unavailable and the voice service of the IMS is unavailable, send a response message to the terminal device, wherein the response message is used to indicate that the terminal device resides in the first network, and the first network provides data services for the terminal device.

[0042] In conjunction with the fifth aspect, in a possible implementation, the information indicating that the voice service of the IMS is unavailable includes statistical information of signaling messages between the terminal device and the SBC in the IMS, and the statistical information is used to determine whether the voice service of the IMS is available.

[0043] In conjunction with the fifth aspect, in a possible implementation, the system further includes a user plane network element;

[0044] The user plane network element is used to send statistical information to the session management network element. The statistical information is the statistical information of the signaling messages between the terminal device and the SBC in the IMS;

[0045] The session management network element is also used to determine that the IMS voice service is unavailable based on statistical information.

[0046] In combination with the fifth aspect, in one possible implementation method, the statistical information is the success rate of voice registration requests or voice call requests corresponding to at least one SBC address, and the session management network element is specifically used to determine that the voice service of the IMS is unavailable when the success rate of voice registration requests or voice call requests corresponding to at least one SBC address is less than a first threshold.

[0047] With reference to the fifth aspect, in a possible implementation, the response message includes information indicating that the voice service of the IMS is unavailable.

[0048] In conjunction with the fifth aspect, in a possible implementation, the mobility management network element is further configured to determine that the CS voice service is unavailable based on a voice service registration success rate corresponding to the MSC.

[0049] In a sixth aspect, an embodiment of the present application provides a communication device for executing the method in the first aspect or any possible implementation of the first aspect. The communication device includes a unit having the function of executing the method in the first aspect or any possible implementation of the first aspect.

[0050] In a seventh aspect, an embodiment of the present application provides a communication device for executing the method in the second aspect or any possible implementation of the second aspect. The communication device includes a unit having the function of executing the method in the second aspect or any possible implementation of the second aspect.

[0051] In an eighth aspect, an embodiment of the present application provides a communication device for executing the method in the third aspect or any possible implementation of the third aspect. The communication device includes a unit having the function of executing the method in the third aspect or any possible implementation of the third aspect.

[0052] In a ninth aspect, an embodiment of the present application provides a communication device for executing the method in the fourth aspect or any possible implementation of the fourth aspect. The communication device includes a unit having the function of executing the method in the fourth aspect or any possible implementation of the fourth aspect.

[0053] In the sixth aspect or the seventh aspect or the eighth aspect or the ninth aspect, the above-mentioned communication device and the communication device may include a transceiver unit and a processing unit.

[0054] In a tenth aspect, an embodiment of the present application provides a communication device, comprising a processor configured to execute the method described in any one of the first to fourth aspects or any possible implementation thereof. Alternatively, the processor is configured to execute a program stored in a memory, and when the program is executed, the method described in any one of the first to fourth aspects or any possible implementation thereof is executed.

[0055] In a possible implementation, the memory is located outside the communication device.

[0056] In a possible implementation, the memory is located within the above-mentioned communication device.

[0057] In an embodiment of the present application, the processor and the memory may also be integrated into one device, that is, the processor and the memory may also be integrated together.

[0058] In a possible implementation, the communication device further includes a transceiver, where the transceiver is configured to receive a signal or send a signal.

[0059] In the eleventh aspect, an embodiment of the present application provides a communication device, which includes a logic circuit and an interface, wherein the logic circuit and the interface are coupled; the interface is used to input a message for registering a CS voice service; and the logic circuit is used to output a response message through the interface when CS voice is unavailable.

[0060] It can be understood that, with respect to the communication device shown in the eleventh aspect, reference can also be made to the first aspect or the specific implementation shown below.

[0061] In a twelfth aspect, an embodiment of the present application provides a communication device, which includes a logic circuit and an interface, wherein the logic circuit and the interface are coupled; the logic circuit is used to obtain statistical information of signaling messages between a terminal device and an SBC in an IMS; and the interface is used to output the statistical information.

[0062] It can be understood that with respect to the communication device shown in the twelfth aspect, reference can also be made to the second aspect or the specific implementation shown below.

[0063] In a thirteenth aspect, an embodiment of the present application provides a communication device, which includes a logic circuit and an interface, wherein the logic circuit and the interface are coupled; the interface is used to output a message for registering a CS voice service and input a response message.

[0064] It can be understood that with respect to the communication device shown in the thirteenth aspect, reference can also be made to the third aspect or the specific implementation shown below.

[0065] In a fourteenth aspect, an embodiment of the present application provides a communication device, comprising a logic circuit and an interface, wherein the logic circuit and the interface are coupled; the interface is used to input statistical information; the logic circuit is used to determine that the voice service of the IMS is unavailable based on the statistical information; and the interface is further used to output information indicating that the voice service of the IMS is unavailable.

[0066] It can be understood that with respect to the communication device shown in the fourteenth aspect, reference can also be made to the fourth aspect or the specific implementation shown below.

[0067] In the fifteenth aspect, an embodiment of the present application provides a computer-readable storage medium for storing a computer program, which, when run on a computer, enables the method shown in any one of the above-mentioned first to fourth aspects or any possible implementation to be executed.

[0068] In the sixteenth aspect, an embodiment of the present application provides a computer program product, which includes a computer program. When the computer program is run on a computer, the method shown in any aspect of the first to fourth aspects or any possible implementation is executed.

[0069] In the seventeenth aspect, an embodiment of the present application provides a computer program. When the computer program is run on a computer, the method shown in any aspect of the first to fourth aspects or any possible implementation is executed. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] The following is an introduction to the drawings related to the embodiments of this application.

[0071] FIG1A is a schematic diagram of a 5G network architecture provided in an embodiment of the present application;

[0072] FIG1B is a schematic diagram of a 4G network architecture provided in an embodiment of the present application;

[0073] FIG2 is a schematic diagram of the structure of a communication system provided in an embodiment of the present application;

[0074] FIG3 is a flow chart of a communication method provided in an embodiment of the present application;

[0075] FIG4 is a flow chart of another communication method provided in an embodiment of the present application;

[0076] FIG5A is a schematic diagram of a voice registration process provided in an embodiment of the present application;

[0077] FIG5B is a schematic diagram of another voice registration process provided in an embodiment of the present application;

[0078] FIG5C is a schematic diagram of a voice call process provided by an embodiment of the present application;

[0079] FIG5D is a schematic diagram of another voice call process provided in an embodiment of the present application;

[0080] FIG5E is a schematic diagram of another voice call process provided in an embodiment of the present application;

[0081] FIG6 is a flow chart of another communication method provided in an embodiment of the present application;

[0082] FIG7 is a schematic diagram of the structure of a communication system provided in an embodiment of the present application;

[0083] FIG8 is a schematic structural diagram of a communication device provided in an embodiment of the present application;

[0084] FIG9 is a schematic structural diagram of another communication device provided in an embodiment of the present application;

[0085] FIG10 is a schematic structural diagram of another communication device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0086] The terms "first" and "second" in the specification, claims and drawings of this application are only used to distinguish different objects, and are not used to limit the order, timing, priority or importance of multiple objects. In the embodiments of the present application, "multiple" refers to two or more. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally also includes steps or units that are not listed, or optionally also includes other steps or units inherent to these processes, methods, products or devices. In addition, the character " / ", unless otherwise specified, generally indicates that the objects associated before and after are in an "or" relationship.

[0087] References to "embodiments" herein mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it refer to independent or alternative embodiments that are mutually exclusive of other embodiments. It will be understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0088] It should be understood that in the present application, "at least one (item)" refers to one or more, "more than one" refers to two or more, "at least two (items)" refers to two or three and more than three, and "and / or" is used to describe the association relationship of associated objects, indicating that three relationships may exist. For example, "A and / or B" can mean: only A exists, only B exists, and A and B exist at the same time, where A and B can be singular or plural. The character " / " generally indicates that the previous and next associated objects are in an "or" relationship. "At least one of the following items" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, at least one of a, b or c can mean: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, c can be single or multiple.

[0089] The method provided in this application can be applied to various communication systems, for example, the Internet of Things (IoT) system, the narrowband Internet of Things (NB-IoT) system, the long term evolution (LTE) system, the fifth generation (5G) communication system, and new communication systems (such as 6G) that will emerge in future communication developments.

[0090] The terminal device in the embodiments of the present application may also be referred to as user equipment (UE), terminal, etc. A terminal device is a device with wireless transceiver capabilities that can be deployed on land, including indoors or outdoors, handheld, wearable, or vehicle-mounted; can also be deployed on water, such as on a ship; can also be deployed in the air, such as on an airplane, balloon, or satellite. The terminal device can be a mobile phone, a tablet computer, a computer with wireless transceiver capabilities, a virtual reality (VR) terminal device, an augmented reality (AR) terminal device, a wireless terminal in industrial control, a wireless terminal in self-driving, a wireless terminal in remote medical care, a wireless terminal in a smart grid, a wireless terminal in transportation safety, a wireless terminal in a smart city, a wireless terminal in a smart home, customer-premises equipment (CPE), etc. It is understandable that the terminal device can also be a terminal device in a future 6G network or a terminal device in a future evolved PLMN, etc.

[0091] It can be understood that the terminal device shown in this application can not only include vehicles in the Internet of Vehicles (such as complete vehicles), but also include vehicle-mounted devices or vehicle-mounted terminals in the Internet of Vehicles. This application does not limit the specific form of the terminal device when applied to the Internet of Vehicles.

[0092] The architecture of the 5G network can be shown in Figure 1A. The 5G network may include an access network and a 5G core network (CN). The access network is used to implement functions related to wireless access, and mainly includes access network (AN) equipment. The access network equipment includes radio access network (RAN) equipment and other equipment accessed through the air interface (such as WiFi). The 5G core network mainly includes the following key logical network elements (or network functions (NF)): user plane function (UPF), access and mobility management function (AMF), session management function (SMF), policy control function (PCF), and unified data management function (UDM). The system may also include one or more of user equipment (UE), data network (DN) and application function (AF). The interface between each network element is shown in Figure 1A. It should be understood that service-based interfaces can also be used for communication between network elements.

[0093] AN equipment is a device that connects terminal devices to a wireless network. It can also be called access network equipment, network equipment, or RAN node. Specifically, it can be a base station. Base stations can include various types of base stations, such as macro base stations, micro base stations (also known as small base stations), relay stations, and access points. Specifically, it can be: an access point (AP) in a wireless local area network (WLAN), a base transceiver station (BTS) in a global system for mobile communications (GSM) or code division multiple access (CDMA), a base station (NodeB, NB) in wideband code division multiple access (WCDMA), an evolved Node B (eNB or eNodeB) in LTE, or a relay station or access point, or a vehicle-mounted device, a wearable device, and the next generation Node B (gNB) in a 5G system, a base station in a future evolved public land mobile network (PLMN) network, an access network device or a module of an access network device in an open access network ORAN (ORAN) system, or a base station in a future mobile communication system or an access node in a WiFi system, etc.

[0094] Optionally, in some deployments of access network devices, the access network devices may include a centralized unit (CU) and a distributed unit (DU). In other deployments of access network devices, the CU may be further divided into a CU-control plane (CP) and a CU-user plan (UP). In yet other deployments of access network devices, the access network device may be an antenna unit (RU). In yet other deployments of access network devices, the access network device may be an open radio access network (ORAN) architecture. The embodiments of the present application do not limit the specific deployment method of the access network device. For example, when the access network device is an ORAN architecture, the access network device shown in the embodiments of the present application may be an access network device in the ORAN, or a module in the access network device. In the ORAN system, the CU may also be referred to as an open (O)-CU, the DU may also be referred to as an O-DU, the CU-CP may also be referred to as an O-CU-CP, the CU-UP may also be referred to as an O-CU-UP, and the RU may also be referred to as an O-RU.

[0095] UDM has the functions of managing user contract data and generating user authentication information.

[0096] The AMF is primarily responsible for UE registration management, UE connection management, UE reachability management, UE access authorization and authentication, UE security, UE mobility management, network slice selection, and SMF selection. The AMF serves as the anchor point for N1 / N2 signaling connections and routes N1 / N2 session management (SM) messages for the SMF, maintaining and managing UE status information. The AMF is a mobility management network element in the 5G system.

[0097] The SMF is responsible for all control plane functions related to UE session management, including selection and control of the UPF, allocation and management of Internet Protocol (IP) addresses, session Quality of Service (QoS) management, and obtaining policy and charging control (PCC) policies from the PCF. The SMF also serves as the termination point for the SM portion of non-access stratum (NAS) messages.

[0098] PCF has the function of providing policy rules to the control plane functional entity.

[0099] AF may be an application server, which may belong to an operator or a third party.

[0100] The UPF is primarily responsible for processing user messages, such as forwarding and billing. It can serve as the anchor point for protocol data unit (PDU) session connections, namely the PDU session anchor (PSA). It is responsible for UE data message filtering, data transmission / forwarding, rate control, billing information generation, user plane QoS processing, uplink transmission authentication, transmission level verification, downlink data packet caching, and downlink data notification triggering. The UPF can also serve as a branch point for multi-homed PDU sessions.

[0101] A DN is a network that provides data transmission services to users, such as Internet Protocol (IP) Multimedia Service (IMS) and the Internet. A DN can include an application server (AS), a software framework that provides an environment for application execution and offers services such as security, data and transaction support, and load balancing for large-scale distributed system management. UEs communicate with the AS to obtain application messages. It should be noted that the AF described above is the control plane of the AS.

[0102] Exemplarily, the architecture of a 4G network may be as shown in FIG1B . The 4G network may include a 4G core network and an access network. The 4G core network mainly includes: a mobility management entity (MME), a serving gateway (SGW / S-GW), a packet data network gateway (PDN GW / PGW / P-GW), a home subscriber server (HSS), a serving GPRS support node (SGSN), a policy and charging rules function (PCRF), and the operator's IP services (for example, IP multimedia subsystem (IMS), packet switching service (PSS)), etc. The core network may be an evolved packet core (EPC). The access network includes an evolution UMTS terrestrial radio access network (E-UTRAN). The access network part mainly includes: access network (Radio Access Network, RAN) equipment. In addition, Figure 1B may also include terminal equipment.

[0103] Among them, MME: is responsible for managing and storing the mobility management context of terminal devices (for example, the terminal device's identification, mobility management status, and user security parameters, etc.), processing non-access stratum (NAS) signaling (for example, attach request, update location request, service request, and packet data network connection request (PDN connectivity request), etc.), and is responsible for the security of NAS signaling.

[0104] SGW: A gateway that terminates the user plane interface of the access network and performs legal monitoring, packet data routing, etc. The interface between the serving gateway SGW and the mobility management entity MME is the S11 interface, which is responsible for the interaction of session control information of terminal devices.

[0105] PGW: A gateway that terminates the SGi interface to the packet data network. It provides user bearer control, data forwarding, IP address allocation, and non-3GPP user access. It serves as the anchor point for both 3GPP and non-3GPP access to the public data network (PDN). The PGW performs packet routing and forwarding functions and is responsible for policy-based charging enhancements and per-user packet filtering. The PGW connects to the S-GW via the S5 interface, transmitting control information such as message creation, modification, and deletion, as well as packet data routing. Furthermore, the PGW connects to the operator's IP services via the SGi interface.

[0106] HSS: The core database that stores user information in the user's home network. The HSS primarily contains user profiles, user subscription data, information related to user authentication and authorization, and information about the user's physical location. The HSS connects to the MME via the S6a interface, allowing the MME to obtain information such as user profiles and subscription data from the HSS.

[0107] PCRF: The policy and charging control decision point for service data flows and IP bearer resources. It controls user and service quality of service (QoS) to provide differentiated services. The PCRF is connected to the PGW via Gx and to the operator's IP services via Rx.

[0108] In addition, the aforementioned MME connects to the E-UTRAN via the S1-MME interface, and the S-GW connects to the E-UTRAN and MME via S1-U and S11, respectively. Simultaneously, the MME connects to the 2G / 3G network via the S3 interface, and the S-GW connects to the SGSN via the S4 interface, respectively, responsible for the control plane anchor and user plane anchor functions for terminal device mobility between the corresponding networks. Furthermore, the S-GW connects to the evolved universal terrestrial radio access network (UTRAN) via the S12 interface.

[0109] It should be noted that the above 4G network architecture diagram is only schematic. In an actual network, there may be multiple similar network elements, for example, there may be multiple access network devices, multiple MMEs, and multiple PCRFs. Among the multiple similar network elements, some network elements may have been upgraded (in each embodiment of the present application, "upgraded" is used to indicate that the network element supports the user plane security on-demand protection mechanism, which will not be repeated below), while some network elements have not been upgraded (these network elements may also be referred to as traditional network elements (legacy Network element, legacy NE), or NE that does not support user plane security on-demand protection). For example, there may be upgraded MMEs and non-upgraded MMEs in the network at the same time.

[0110] In some scenarios, the above-mentioned 4G network and 5G network can interwork (Interworking), and the network elements of the 4G core network and the network elements in the 5G core network can be co-located. For example, the UPF in the 5G network and the PDN gateway user plane function (PDN gateway user plane function, PGW-U) in the 4G network can be co-located. As another example, the SMF in the 5G network and the PDN gateway control plane function (PDN gateway control plane function, PGW-C) in the 4G network can be co-located. As another example, the PCF in the 5G network and the PCRF in the 4G network can be co-located. As another example, the UDM in the 5G network and the HSS in the 4G network can be co-located. As another example, the AMF in the 5G network and the MME in the 4G network can be co-located. As another example, the UDM in the 5G network and the HSS in the 4G network can be co-located.

[0111] It is understood that the term "combined" here can mean that the same device simultaneously possesses the functions of two entities. In the embodiments of this application, for ease of description, the MME and AMF may be referred to as mobility management network elements, the PGW-C and SMF may be referred to as session management network elements or control plane network elements, and the PGW-U and UPF may be referred to as user plane network elements. These terms are used for this purpose and will not be further elaborated below. Of course, the aforementioned combined network devices may also be referred to by other names, and this embodiment of the application does not specifically limit this.

[0112] It is understandable that there may be other network elements in the intercommunication architecture of the 4G network and the 5G network. For example, the 4G network may also include a general packet radio system (GPRS) service support node (Serving GPRS support node, SGSN), etc., and the 5G network may also include an authentication service function (AUSF) entity and a network slice selection function (NSSF) entity, etc. The embodiments of the present application do not make specific limitations on this.

[0113] It should be noted that the above 4G network and 5G network interoperability architecture is only schematic. In an actual network, there may be multiple similar network elements, for example, multiple access network devices and multiple MMEs.

[0114] It should be noted that the interface names between the various network elements in Figure 1A and Figure 1B are only examples. The interface names may be other names in the specific implementation, and the embodiments of the present application do not specifically limit this. The embodiments of the present application are not limited to application only in the system architecture shown in Figure 1A or Figure 1B. For example, a communication system to which the message transmission method of the embodiments of the present application can be applied may include more or fewer network elements or devices. The devices or network elements in Figure 1A or Figure 1B can be hardware, or functionally divided software, or a combination of the two. The devices or network elements in Figure 1A or Figure 1B can communicate with each other through other devices or network elements.

[0115] Figure 2 is an example of a communication system based on voice services provided in an embodiment of the present application. As shown in Figure 2, the communication system may include a voice domain, a 4G network, and a 5G network. Among them, the voice domain includes a CS network and an IMS network. The 4G network includes an eNB, an MME, an SGW-U, an SGW, a PGW-C, and a PGW-U. The 5G network includes a gNB, an AMF, an SMF, and an UPF. The CS network includes an MSC, which is used to register CS voice. The IMS network includes or SBC, which is used to register IMS voice. Exemplarily, the MSC can be co-located with the VLR, referred to as MSC / VLR. The SBC can be co-located with the call session control function (CSCF), referred to as CSCF / SBC.

[0116] The 4G network can provide voice services for terminal devices based on the CS network and the IMS network. For terminal devices accessing the 4G network, the terminal device can send a joint registration request to the MME through the eNB. The joint registration request is used to request CS voice services and data services. After receiving the joint registration request, the MME sends a CS voice registration request to the MSC or VLR to register the terminal device for CS voice. The terminal device can also send an IMS registration request to the MME through the eNB. After receiving the IMS registration request, the MME can send an IMS registration request to the SBC or CSCF in the IMS network through the SGW, PGW-C, and PGW-U to register the terminal device for IMS voice. After the terminal device successfully jointly registers, the 4G network can provide the terminal device with circuit switched fallback (CSFB) so that when the IMS voice service is unavailable, the terminal device can perform voice services based on CS voice. During the IMS voice call process of the terminal device, the terminal device's IMS call request and voice data can be transmitted to the CSCF or SBC through the eNB, SGW-U, and PGW-U.

[0117] Voice solutions for 5G networks can include evolved packet system fallback (EPS FB) and voice over new radio (VoNR) over new radio (NR). VoNR refers to voice services carried on NR, with both the terminal device's voice and data services carried on NR. EPS FB means that 5G NR does not carry voice services. When a terminal device initiates or receives a voice call in 5G NR, it falls back to the 4G network through redirection or handover, with VoLTE providing voice services. In a 5G network using VoNR, the terminal device can send an IMS voice registration request to the AMF via the gNB. The AMF sends an IMS registration request to the SBC or CSCF in the IMS network via the SMF and UPF to register the terminal device for IMS voice. During an IMS voice call, the terminal device's IMS call request and voice data can be transmitted to the CSCF or SBC via the gNB and UPF.

[0118] Exemplarily, the terminal device can register with the network in a voice-prefer mode. When the network where the terminal device resides cannot provide voice services, the terminal device can try voice registration on other networks. As shown in Figure 2, IMS voice involves many network elements, and any overload or failure of the network element will cause the IMS voice service to be unavailable, such as an IMS network failure. For terminal devices in a 4G network, when the voice service of the IMS system is unavailable, the 4G network can provide voice services for the terminal device based on CS voice. When both CS voice and IMS voice are unavailable, the terminal device cannot reside in the 4G network, which will cause the data service of the terminal device to not operate normally. For terminal devices in a 5G network, when the voice service of the IMS is unavailable, the terminal device cannot reside in the 5G network, which will cause the data service of the terminal device to not operate normally.

[0119] In view of this, embodiments of the present application provide a communication method, a communication system, and a communication device that can ensure that data services of terminal devices are carried out normally. The method provided in embodiments of the present application can be applied to the communication system shown in FIG1A , FIG1B , or FIG2 .

[0120] It is understood that although the method shown below does not involve a relay node, those skilled in the art will appreciate that when a sender and receiver communicate, a forwarding operation can be performed through a relay node. For example, in an embodiment of the present application, information exchange between a terminal device and a mobility management network element can be forwarded through an access network device, which will not be described in detail below.

[0121] It is understood that the interaction diagrams in this application use network devices and terminal devices as examples of the execution entities of the interaction diagrams to illustrate the method, but this application does not limit the execution entities of the interaction diagrams. For example, the network device in the interaction diagram can also be a chip, chip system, or processor that supports the network device to implement the method, or a logical node, logic module, or software that can implement all or part of the network device functions; the terminal device in the interaction diagram can also be a chip, chip system, or processor that supports the terminal to implement the method.

[0122] Please refer to Figure 3, which is a flow chart of a communication method provided in an embodiment of the present application. As shown in Figure 3, the method includes but is not limited to the following steps.

[0123] 301. The terminal device sends a message for registering the CS voice service. Correspondingly, the mobility management network element receives the message for registering the CS voice service.

[0124] Exemplarily, the mobility management network element is a network element in the first network for performing mobility management. The first network can provide CSFB, and the first network can provide voice services for terminal devices based on CS voice. For example, the first network can be the 4G network described above, and the mobility management network element can be an MME, or the mobility management network element can also be a network element jointly set up by an MME and an AMF. The message for indicating the CS voice service can also be called a joint registration message, which is used to register CS voice and data services.

[0125] For example, the first network can provide voice services based on IMS and CS voice. If IMS voice services are unavailable, the first network can provide voice services to the terminal device based on CS voice. After the terminal device resides on the first network, it can register for CS voice and IMS voice services to obtain voice services. For example, the terminal device can send a joint registration request message to the mobility management network element to request the CS voice service.

[0126] 302. When the CS voice service is unavailable, the mobility management network element sends a response message to the terminal device. Correspondingly, the terminal device receives the response message, which is used to indicate that the terminal device resides in the first network, which provides data services for the terminal device.

[0127] Exemplarily, the first network is the network that the terminal device currently resides in. The response message is used to indicate that the CS voice registration of the terminal device is successful.

[0128] Exemplarily, the response message includes information for indicating that the CS voice service is unavailable. For example, the response message may include a first field, and the first field is used to indicate that the CS voice service is unavailable. It is understandable that the first field may be a field defined in the protocol, or a newly added field of the response message, and this application does not impose any restrictions. For example, the first field may be a temporary mobile subscriber identity (TMSI) field, and the response message may include a TMSI field. When the CS voice service is available, the TMSI field includes the TMSI information allocated by the MSC to the terminal device. When the CS voice service is unavailable, the TMSI field may be set to a first value to indicate that the voice service of the IMS is unavailable. The first value is different from the TMSI value, or the first value may be understood as a special TMSI. For example, the first value may be 0000. The embodiment of the present application does not impose any restrictions on the value of the first value.

[0129] In an embodiment of the present application, a response message is sent to the terminal device when the CS voice service is unavailable, and the response message indicates that the CS voice registration of the terminal device is successful, thereby ensuring that the terminal device resides in the first network, so that the first network can provide data services for the terminal device, and ensuring the normal operation of the data service of the terminal device.

[0130] In a possible implementation, the mobility management network element sends a response message to the terminal device when the CS voice service and the IMS voice service are unavailable.

[0131] Illustratively, the response message includes information indicating that the IMS voice service is unavailable. For example, the response message may include a second field indicating that the IMS voice service is unavailable. The second field may be a field defined in the protocol or a newly added field to the response message, and this application does not impose any limitation thereto.

[0132] Exemplarily, the mobility management network element may determine that the voice service of the IMS is unavailable based on an indication of the AMF or PGW-C.

[0133] It is understandable that, when the CS voice service is unavailable and the IMS voice service is available, the mobility management network element may send a message to the terminal device for rejecting registration for the CS voice service.

[0134] In a possible implementation, the mobility management network element may determine that the CS voice service is unavailable based on a voice service registration success rate corresponding to the MSC.

[0135] Exemplarily, after receiving the message sent by the terminal device for registering the CS voice service, the mobility management network element may initiate CS voice registration to the MSC via the SGS interface to register the terminal device with the MSC so that the terminal device can perform voice communications in the CS domain.

[0136] As an example, the voice service registration success rate corresponding to the MSC includes the success rate of voice registration requests sent by the mobility management network element to the MSC or the success rate of CS voice registration initiated by the mobility management network element through the SGS interface between the mobility management network element and the MSC (also referred to as the SGS registration success rate). The mobility management network element may determine whether the CS voice service is available based on the success rate of registration requests between the mobility management network element and the MSC. The mobility management network element may record the number of CS voice registration requests initiated by the mobility management network element to the MSC and the number of registration response messages received from the MSC, thereby determining the SGS registration success rate.

[0137] For example, when the SGS registration success rate is less than the second threshold, the mobility management network element determines that the CS voice service is unavailable and sends a response message to the terminal device, indicating that the terminal device has successfully registered for the CS voice service. When the SGS registration success rate is greater than the second threshold, the mobility management network element determines that the CS voice service is available, and therefore initiates a CS voice registration with the MSC to register the terminal device with the MSC, so that the terminal device can perform voice communications in the CS domain.

[0138] It is understandable that when the SGS registration success rate is equal to the second threshold, the mobility management network element may determine that the CS voice service is unavailable, or the mobility management network element may also determine that the CS voice service is unavailable, which is not limited here.

[0139] As another example, the voice service registration success rate corresponding to an MSC includes the SGS registration success rate and the CS voice registration success rate corresponding to the MSC's area. Specifically, the mobility management network element may determine whether CS voice is available based on the SGS registration success rate and the CS voice registration success rate corresponding to the MSC's area. The SGS registration success rate is determined by the number of successful CS voice registration requests on the SGS interface between the mobility management network element and the MSC, and the CS voice registration success rate corresponding to the MSC's area is determined by the number of successful CS voice registration requests sent by the mobility management network element. The CS voice registration requests sent by the mobility management network element may include CS voice registration requests initiated by the mobility management network element and other messages exchanged with the MSC. The mobility management network element may record received CS voice registration requests and the number of successful CS voice registration requests to determine the CS voice registration success rate corresponding to the MSC's area. The mobility management network element may also determine whether the MSC is available based on the success rate corresponding to the MSC's area. If the mobility management network element determines that the MSC is unavailable, it provides a response message for the CS voice registration on behalf of the MSC.

[0140] Exemplarily, when the SGS registration success rate is less than the second threshold and the CS voice registration success rate corresponding to the MSC area is less than the third threshold, the mobility management network element determines that the CS voice service is unavailable and sends a response message to the terminal device, which is used to indicate that the terminal device has successfully registered for the CS voice service.

[0141] For example, when the CS voice registration success rate corresponding to the MSC area is greater than the third threshold, the mobility management network element may initiate a CS voice registration request to the MSC after receiving the message for registering the CS voice service, without acting as an agent for the MSC to respond to the CS voice registration.

[0142] It can be understood that the second threshold and the third threshold may be predefined by a protocol or configured by the mobility management network element.

[0143] In a possible implementation, the method shown in FIG3 further includes step 303 and step 304 .

[0144] 303 , the terminal device sends a message for registering the voice service of the IMS. Correspondingly, the mobility management network element receives the message for registering the voice service of the IMS.

[0145] 304. The mobility management network element sends a message for rejecting the voice service registration of the IMS. Correspondingly, the terminal device receives the message for rejecting the voice service registration of the IMS.

[0146] For example, when the voice service of IMS is unavailable, the mobility management network element can send a message to the terminal device to reject the registration of the voice service of IMS after receiving the message for registering the voice service of IMS, without initiating an IMS voice registration request to IMS, thereby saving signaling overhead.

[0147] It can be understood that when the voice service of the IMS is available, the mobility management network element initiates an IMS voice registration request to the IMS after receiving the message for registering the voice service of the IMS.

[0148] In some possible implementations, after the mobility management network element determines that the voice service of the IMS is unavailable, the mobility management network element can send an IMS voice registration request message to the IMS at a first frequency to obtain the recovery status of the IMS voice service, so that the IMS voice service can be provided to the terminal device in a timely manner after the IMS voice service is restored.

[0149] In a possible implementation, when the CS voice service and the IMS voice service are unavailable, the mobility management network element further receives a message from the terminal device requesting network attachment, and sends a message to the terminal device accepting network attachment.

[0150] Exemplarily, the message for requesting network attachment (attach) is used to request EPS attachment. The message for requesting network attachment can be an attach request (attach request) message or a joint registration request message. After receiving the message, the mobility management network element performs EPS attachment and establishes a default bearer (default bearer) for the terminal device. The default bearer is used to carry the data service of the terminal device. After completing the establishment of the default bearer, the mobility management network element sends a message for accepting network attachment (Attach Accept) to the terminal device.

[0151] In this implementation, when CS voice services and IMS voice services are unavailable, the terminal device and the mobility management network element can initiate EPS attachment to ensure that the data services of the terminal device can proceed normally.

[0152] Please refer to Figure 4, which is a flow chart of another communication method provided in an embodiment of the present application. As shown in Figure 4, the method includes but is not limited to the following steps.

[0153] 401. The user plane network element obtains statistical information of signaling messages between the terminal device and the SBC in the IMS.

[0154] Exemplarily, the user plane network element may be a user plane forwarding device, configured to forward signaling messages between the access network device and the SBC. For example, the user plane network element may be a UPF or a PGW-U, or the user plane network element may be a combined network element of the UPF and the PGW-U. Signaling messages between the terminal device and the SBC may be forwarded by the access network device and the user plane network element. Signaling messages between the terminal device and the SBC include an IMS voice registration request message initiated by the terminal device, an IMS voice call request message, and a response message returned by the SBC. The user plane network element may monitor and record signaling messages between the terminal device and the SBC to obtain statistical information. The signaling message may be a Session Initiation Protocol (SIP) signaling message.

[0155] Exemplarily, the statistical information may include at least one of a success rate of an IMS voice registration request or an IMS voice call request, the number of IMS voice registration requests or IMS voice call requests, and the number of IMS voice registration responses or IMS voice call responses. The success rate of the IMS voice registration request or IMS voice call request is a ratio of the number of IMS voice registration responses or IMS voice call responses to the number of IMS voice registration requests or IMS voice call requests.

[0156] For example, as shown in Figure 5A, during an unauthenticated IMS voice registration, the terminal device sends a registration request (SEGISTER) message to the SBC. After receiving the registration request message, the SBC can return a 200OK message to the terminal device, thereby completing the IMS voice registration. The user-plane network element records the registration request message and the 200OK message and determines that the IMS voice registration request is successful. If the SBC does not respond with a 200OK message after the terminal device sends the registration request, the user-plane network element records the registration request and determines that the IMS voice registration has failed.

[0157] For another example, as shown in Figure 5B, during the authenticated IMS voice registration process, the terminal device sends a registration request to the SBC. After receiving the registration request, the SBC replies with a "Registration without Authentication" (401unauthorized) message to the terminal device. The terminal device then sends a registration request with authentication information to the SBC. After authentication is successful, the SBC replies with a 200OK message to the terminal device. The user-plane network element monitors and records the signaling messages (such as the registration request message and the 200OK message) during the IMS voice registration process. If the user-plane network element detects the 200OK message, it determines that the IMS voice registration is successful. If the user-plane network element does not detect the 200OK message, it determines that the IMS voice registration has failed.

[0158] For another example, as shown in FIG5C , during the IMS voice call connection process, the terminal device initiates a session invitation (invite with SDP) message based on the session description protocol (SDP). The SBC responds to the terminal device with a 100 trying message, a 180 ringing message, and a 200 OK (200 OK with SDP) message based on SDP. The terminal device responds with an acknowledgement (ACK) message to the SBC, thereby completing the IMS voice call connection. The user plane network element can monitor the session invitation message, 100 trying message, 180 ringing message, 200 OK message, and ACK message. If the session invitation message, 100 trying message, 180 ringing message, 200 OK message, and ACK message are all detected, the user plane network element determines that the IMS voice call request is successful. Otherwise, the user plane network element determines that the IMS voice call request has failed.

[0159] For another example, as shown in Figure 5D, when a terminal device cancels an IMS voice call, the signaling messages between the terminal device and the SBC may include a session invite message, a 180 ringing message, a session cancel message, a 200 OK message for the cancellation, a 487 request terminated message, and an ACK message. The user-plane network element monitors the above signaling messages. If all of the above signaling messages are monitored, it determines that the cancellation of the IMS voice call is successful and the IMS voice call request is successful. Otherwise, it determines that the cancellation of the IMS voice call fails and the IMS voice call request fails.

[0160] For another example, as shown in Figure 5E , when the terminal device is busy during an IMS voice call, the signaling messages between the terminal device and the SBC may include: a session invitation message, a 486 Busy Here message, and an ACK message. The user-plane network element monitors the above signaling messages and determines that the IMS voice call request is successful if all of the above signaling messages are detected; otherwise, the IMS voice call request is determined to have failed.

[0161] It is understood that in the embodiments of the present application, a successful IMS voice call request refers to the IMS successfully responding to the call request initiated by the terminal device, rather than the terminal device successfully connecting with the called party. For example, if an IMS voice call is canceled or the called party is busy, the SBC sends a corresponding response message to the terminal device, confirming that the IMS voice call request is successful.

[0162] 402. The user plane network element sends statistical information to the session management network element. Correspondingly, the session management network element receives the statistical information. The statistical information is used to determine whether the voice service of the IMS is available.

[0163] Exemplarily, the session management network element is used to manage sessions for terminal devices accessing the network from an access network device. For example, the session management network element may be an SMF or a PGW-C, or the session management network element may be a combined SMF and PGW-C network element. The user plane network element may periodically send statistical information to the session management network element, or the user plane network element may send the statistical information based on the success rate of IMS voice registration requests or IMS voice call requests. For example, if the success rate of IMS voice registration requests or IMS voice call requests is less than a first threshold, the user plane network element sends the statistical information to the session management network element.

[0164] As an example, the user plane network element is UPF and the session management network element is SMF. UPF can report the statistical information to SMF through the N4 interface. For example, UPF can carry the statistical information in the process of the packet forwarding control protocol (PFCP) node report procedure (PFCP Node Report Procedure) or the PFCP association update procedure (PFCP Association Update procedure). For example, a third field is included in the PFCP node report request message or the PFCP association update request message, and the third field is used to carry the statistical information. The third field can also include the address information of the SBC (for example, the IP address of the SBC).

[0165] Exemplarily, the third field may be a field in a PFCP node report request message or a PFCP association update request message for reporting statistical information. For example, the third field may be called an SBC report field.

[0166] As another example, the user plane network element is PGW-U, and the session management network element is PGW-C. PGW-U can send the statistical information to PGW-C via the Sxb interface.

[0167] 403. The session management network element sends information indicating that the voice service of the IMS is unavailable to the mobility management network element. Correspondingly, the mobility management network element receives the information indicating that the voice service of the IMS is unavailable from the session management network element.

[0168] As an example, the session management network element determines that the voice service of the IMS is unavailable based on the statistical information, and sends information indicating that the voice service of the IMS is unavailable to the mobility management network element.

[0169] Exemplarily, the statistical information is the success rate of voice registration requests or voice call requests corresponding to at least one SBC address. After receiving the statistical information, the session management network element can compare the success rate of voice registration requests or voice call requests corresponding to at least one SBC address with a first threshold value to determine whether an SBC address is available. If the at least one SBC address is unavailable, the session management network element determines that the voice service of the IMS is unavailable. For example, if the success rate of voice registration requests or voice call requests corresponding to the at least one SBC address is less than the first threshold value, the session management network element determines that the voice service of the IMS is unavailable and sends information indicating that the voice service of the IMS is unavailable to the mobility management network element, or sends information indicating that all SBC addresses are unavailable to the mobility management network element. That is, the information indicating that the voice service of the IMS is unavailable can also be replaced by the description of: information indicating that all SBC addresses are unavailable.

[0170] Exemplarily, the information indicating that all SBC addresses are unavailable may be carried in an interaction message between a session management network element and a mobility management network element. For example, the information indicating that the voice service of the IMS is unavailable may be sent to the mobility management network element via an N1 session management (SM) container including a PDU session release command message, the PDU session release command message including a PDU session identifier (ID) and a PDU session release reason, where the PDU session release reason is set to "all SBC addresses are unavailable."

[0171] For another example, the session management network element may send information indicating that the voice service of the IMS is unavailable to the mobility management network element via the N1N2 transfer application program interface (API) (Namf_Communication_N1N2MessageTransfer) service of the AMF management service. For example, the PDU session release command in the N1 SM container includes a field for indicating that the SBC address is unavailable.

[0172] For another example, the session context status notification API (Nsmf_PDUSession_SMContextStatusNotify) message of the SMF data session service includes a field carrying information indicating that all SBC addresses are unavailable.

[0173] If a first SBC address exists among the at least one SBC address, and the success rate of the voice registration request or voice call request corresponding to the first SBC address is greater than a first threshold, the session management network element determines that the first SBC address is available, that is, the voice service of the IMS is available. Therefore, the session management network element can instruct the terminal device to perform IMS voice registration based on the first SBC address. Exemplarily, the session management network element can initiate a proxy CSCF (P-CSCF) address list update process and instruct the terminal device to retry IMS voice registration based on the first SBC address through an extended protocol configuration (ePCO) message.

[0174] As another example, the information indicating that the voice service of the IMS is unavailable includes the above-mentioned statistical information, which is used to determine whether the voice service of the IMS is available. After receiving the statistical information, the mobility management network element can determine the success rate of the IMS voice registration request or the IMS voice call request based on the statistical information, and determine whether the voice service of the IMS is available based on the success rate of the IMS voice registration request or the IMS voice call request. For example, if the success rate of the IMS voice registration request or the IMS voice call request is less than a first threshold, the mobility management network element determines that the voice service of the IMS is unavailable. If the success rate of the IMS voice registration request or the IMS voice call request is greater than the first threshold, the mobility management network element determines that the voice service of the IMS is available.

[0175] It is understandable that the specific implementation manner in which the mobility management network element determines that the IMS voice service is unavailable based on statistical information can refer to the specific implementation manner in which the session management network element determines that the IMS voice service is unavailable based on statistical information above, which will not be repeated here.

[0176] It can be understood that in the embodiment of the present application, the success rate of the voice registration request or voice call request corresponding to the first SBC address refers to the ratio of the number of successful responses to the voice registration request or voice call request whose destination SBC address is the first SBC address to the number of requests for the voice registration request or voice call request whose destination SBC address is the first SBC address.

[0177] In one possible implementation, the mobility management network element may store information indicating that the IMS voice service is unavailable, and upon receiving a message from a terminal device for registering the IMS voice service, reply to the terminal device with a message rejecting the registration for the IMS voice service, without the need to send an IMS voice registration request to the IMS, thereby saving signaling overhead.

[0178] In some possible implementations, after the mobility management network element determines that the voice service of the IMS is unavailable, the mobility management network element can send an IMS voice registration request message to the IMS at a first frequency to obtain the recovery status of the IMS voice service, so that the IMS voice service can be provided to the terminal device in a timely manner after the IMS voice service is restored.

[0179] 404. The terminal device sends a message for registering the CS voice service. Correspondingly, the mobility management network element receives the message for registering the CS voice service.

[0180] 405. When the CS voice service and the IMS voice service are unavailable, the mobility management network element sends a response message to the terminal device. Accordingly, the terminal device receives the response message, which is used to indicate that the terminal device resides in the first network, which provides data services for the terminal device.

[0181] It is understandable that the specific implementation of step 404 and step 405 can refer to the specific implementation of step 301 and step 302 in Figure 3, and will not be described in detail here.

[0182] In this embodiment of the present application, the success rate of IMS voice registration requests or IMS voice call requests can be monitored by a user-plane network element, and the availability of IMS voice services can be accurately determined based on the success rate of the IMS voice registration requests or IMS voice call requests. Furthermore, if the CS voice service is unavailable, a registration response message is sent to the terminal device, indicating the successful CS voice registration to the terminal device via the response message. This ensures that the terminal device remains in the first network, preventing data service unavailability caused by the terminal device being disconnected from the network. In other words, even if voice services are unavailable, the normal operation of the terminal device's data services can be guaranteed.

[0183] Please refer to Figure 6, which is a flow chart of another communication method provided in an embodiment of the present application. As shown in Figure 6, the method includes but is not limited to the following steps.

[0184] 601. UPF sends first statistical information to SMF, and correspondingly, SMF receives the first statistical information.

[0185] Exemplarily, the first statistical information includes statistical information of signaling messages whose destination SBC address is the SBC address corresponding to the SMF. For example, the first statistical information includes one or more of the following: the success rate of the voice registration request or voice call request corresponding to the SBC address corresponding to the SMF, the number of voice registration requests or voice call requests corresponding to the SBC address corresponding to the SMF, and the number of responses to the voice registration request or voice call request corresponding to the SBC address corresponding to the SMF. The SBC address corresponding to the SMF is the SBC address locally configured by the SMF. The SMF can be configured with multiple SBC addresses (also referred to as an SBC address pool) and send the locally configured SBC address to the terminal device. When the terminal device resides in a 5G network, it can initiate a voice registration request or a voice call request based on the SBC address sent by the SMF.

[0186] It can be understood that the specific implementation method of the UPF obtaining the first statistical information can refer to the specific implementation method of step 401 in Figure 4, which will not be described in detail here.

[0187] In a possible implementation, the method shown in FIG6 includes step 602 and step 603 .

[0188] 602. SMF sends information indicating that the SBC address is unavailable to AMF. Correspondingly, AMF receives the information indicating that the SBC address is unavailable.

[0189] Exemplarily, the SMF determines whether there is an available SBC address in the SBC address pool based on the first statistical information. If there is no available SBC address in the SBC address pool, the SMF sends information indicating that the SBC address is unavailable to the AMF, thereby indicating that the IMS voice service is unavailable. If there is an available SBC address in the SBC address pool, the SMF may instruct the terminal device to change the SBC address and retry IMS voice registration.

[0190] It is understandable that the specific implementation of step 602 can also refer to the specific implementation of step 403 in Figure 4, which will not be described in detail here.

[0191] 603. AMF sends information indicating that the 5G network service is unavailable to the terminal device. Accordingly, the terminal device receives the information indicating that the 5G network service is unavailable for the terminal.

[0192] Exemplarily, after receiving the information indicating that the SBC address is unavailable, the AMF sends information indicating that the service of the 5G network is unavailable to the terminal device, instructing the terminal device to fall back to the 4G network (i.e., instructing the terminal device to access the 4G network). For example, the AMF can send a user re-registration message to the terminal device, and instruct the terminal device to fall back to the 4G network through the cause value (such as: #15 / #27) carried by the user re-registration message. The terminal device can access the 4G network based on the instruction of the AMF and perform voice registration on the 4G network.

[0193] Exemplarily, the AMF may save information that the SBC address is unavailable, and after receiving an IMS voice registration request from the terminal device, send a message (e.g., a user re-registration message) to the terminal device for rejecting the IMS voice registration, and instruct the terminal device to fall back to the 4G network through the message for rejecting the IMS voice registration.

[0194] In another possible implementation, if the SMF determines that the SBC address is unavailable, it instructs the terminal device to fall back to the 4G network. For example, the SMF may initiate a P-CSCF address list update procedure, wherein the P-CSCF address field in the ePCO message is empty. The empty P-CSCF address in the ePCO message instructs the terminal device to retry CS registration, so that the terminal device falls back to the 4G network.

[0195] 604. The PGW-U sends the second statistical information to the PGW-C. Correspondingly, the PGW-C receives the second statistical information.

[0196] Exemplarily, the second statistical information includes statistical information of signaling messages whose destination SBC address is the SBC address corresponding to the PGW-C. The PGW-U can forward and monitor signaling messages whose destination address is the SBC address corresponding to the PGW-C to obtain the second statistical information. For example, the second statistical information includes one or more of the following: the success rate of voice registration requests or voice call requests corresponding to the SBC address corresponding to the PGW-C, the number of voice registration requests or voice call requests corresponding to the SBC address corresponding to the PGW-C, and the number of responses to voice registration requests or voice call requests corresponding to the SBC address corresponding to the PGW-C.

[0197] It is understandable that the specific implementation of step 604 can also refer to the specific implementation of step 402 in Figure 4, which will not be described in detail here.

[0198] 605 , the PGW-C sends information indicating that the SBC address is unavailable to the MME. Correspondingly, the MME receives the information indicating that the SBC address is unavailable.

[0199] Exemplarily, the PGW-C determines whether the SBC address corresponding to the PGW-C is available based on the second statistical information. If none of the SBC addresses corresponding to the PGW-C are available, the PGW-C sends information to the MME indicating that the SBC address is unavailable. If an available SBC address exists, the PGW-C instructs the terminal device to change the SBC address and re-initiate a voice registration request.

[0200] Exemplarily, the MME may store the information that the SBC address is unavailable, and after receiving a message for registering the IMS voice service from the terminal device, send a message for rejecting the IMS registration to the terminal device.

[0201] It is understandable that the specific implementation of step 605 can also refer to the specific implementation of step 403 in Figure 4, which will not be described in detail here.

[0202] 606. The terminal device sends a message for registering CS voice to the MME. Correspondingly, the MME receives the message for registering CS voice.

[0203] 607. When the CS voice service and the IMS voice service are unavailable, the MME sends a response message to the terminal device, and the terminal device receives the response message. The response message is used to indicate that the terminal device resides on the first network, which provides data services for the terminal device.

[0204] It is understandable that the specific implementation of step 606 and step 607 can refer to the specific implementation of step 301 and step 302 in Figure 3, and will not be described in detail here.

[0205] In an embodiment of the present application, for a terminal device in a 5G network, when the IMS voice service in the 5G network is unavailable, the SMF or AMF can instruct the terminal device to fall back to the 4G network, thereby unifying the behavior of the terminal device when the IMS voice service is unavailable. Furthermore, when the CS voice service is unavailable, a registration response message is sent to the terminal device, indicating through the response message that the CS voice registration is successful, thereby ensuring that the terminal device resides in the first network and preventing the terminal device from being disconnected from the network and causing data service unavailability. That is, when the voice service is unavailable, the normal operation of the terminal device's data service can be guaranteed.

[0206] In the embodiment of the present application, the SBC may be replaced by a P-CSCF, and the SBC address may be replaced by the P-CSCF. For example, a terminal device may send an IMS voice registration request or an IMS voice call request to the P-CSCF, and the UPF may be used to forward and record signaling messages between the terminal device and the P-CSCF.

[0207] Please refer to Figure 7, which is a schematic diagram of the structure of a communication system provided in an embodiment of the present application. The communication system 70 includes a session management network element 701 and a mobility management network element 702.

[0208] The session management network element 701 is configured to send information indicating that the voice service of the IMS is unavailable to the mobility management network element 702 .

[0209] The mobility management network element 702 is used to receive a message from the terminal device for registering the CS voice service, and when the CS voice service is unavailable and the IMS voice service is unavailable, send a response message to the terminal device, where the response message is used to indicate that the terminal device resides in the first network, and the first network provides data services for the terminal device.

[0210] In a possible implementation, the information indicating that the voice service of the IMS is unavailable includes statistical information of signaling messages between the terminal device and the SBC in the IMS, and the statistical information is used to determine whether the voice service of the IMS is available.

[0211] In a possible implementation, the communication system 70 further includes a user plane network element 703;

[0212] The user plane network element 703 is used to send statistical information to the session management network element 701, where the statistical information is the statistical information of the signaling messages between the terminal device and the SBC in the IMS;

[0213] The session management network element 701 is further configured to determine that the IMS voice service is unavailable based on statistical information.

[0214] In one possible implementation, the statistical information is a success rate of a voice registration request or a voice call request corresponding to at least one SBC address, and the session management network element 701 is specifically used to determine that the voice service of the IMS is unavailable when the success rate of the voice registration request or the voice call request corresponding to at least one SBC address is less than a first threshold.

[0215] In a possible implementation, the response message includes information indicating that the voice service of the IMS is unavailable.

[0216] In a possible implementation, the mobility management network element 702 is further configured to determine that the CS voice service is unavailable based on a voice service registration success rate corresponding to the MSC.

[0217] It is understandable that the specific implementation of the above mobility management network element 702, session management network element 701 and user plane network element 703 can also refer to the above method embodiments (such as the methods shown in Figures 3, 4 and 6), which will not be described in detail here.

[0218] The following describes the device provided in the embodiments of the present application.

[0219] The present application divides the functional modules of the communication device according to the above-mentioned method embodiment. For example, each functional module can be divided according to each function, or two or more functions can be integrated into one processing module. The above-mentioned integrated modules can be implemented in the form of hardware or in the form of software functional modules. It should be noted that the division of modules in this application is schematic and is only a logical functional division. There may be other division methods in actual implementation. The communication device of the embodiment of the present application will be described in detail below with reference to Figures 8 to 10.

[0220] Figure 8 is a schematic diagram of the structure of a communication device provided in an embodiment of the present application. As shown in Figure 8, the communication device includes a processing unit 801 and a transceiver unit 802. The transceiver unit 802 can implement corresponding communication functions, and the processing unit 801 is used to process data. For example, the transceiver unit 802 can also be referred to as a communication interface or a communication unit.

[0221] In some embodiments of the present application, the communication device can be used to execute the actions performed by the mobility management network element in the above method embodiment. In this case, the communication device can be a mobility management network element, or the communication device can be a component that can be configured in the mobility management network element (such as a chip or system, etc.). The transceiver unit 802 is used to execute the operations related to the transmission and reception of the mobility management network element in the above method embodiment, and the processing unit 801 is used to execute the operations related to the processing of the mobility management network element in the above method embodiment.

[0222] Illustratively, the transceiver unit 802 is configured to receive a message for registering for the CS voice service; the processing unit 801 is configured to send a response message via the transceiver unit 802 when the CS voice service is unavailable.

[0223] Optionally, the transceiver unit 802 is further configured to receive information indicating that the voice service of the IMS is unavailable.

[0224] Optionally, the transceiver unit 802 is further configured to receive a message indicating a voice service of the IMS, and send a message for rejecting registration of the voice service of the IMS.

[0225] Optionally, the processing unit 801 is further configured to determine that the CS voice service is unavailable based on a voice service registration success rate corresponding to the MSC.

[0226] It can be understood that for specific descriptions of the message for indicating the CS voice service, the response message, the information for indicating that the IMS voice service is unavailable, the message for indicating the IMS voice service, the message for refusing to register for the IMS voice service, etc., reference can be made to the method embodiments shown above (such as the method shown in Figure 3, Figure 4 or Figure 6), and will not be described in detail here.

[0227] In other embodiments of the present application, the communication device can be used to execute the actions performed by the user plane network element in the above method embodiment. In this case, the communication device can be a user plane network element, or the communication device can be or can be configured as a component of the user plane network element (such as a chip or system, etc.), and the transceiver unit 802 is used to execute the operations related to the transmission and reception of the user plane network element in the above method embodiment, and the processing unit 801 is used to execute the operations related to the user plane network element processing in the above method embodiment.

[0228] Exemplarily, the processing unit 801 is configured to obtain statistical information of signaling messages between the terminal device and the SBC in the IMS; the transceiver unit 802 is configured to send the statistical information.

[0229] It is understandable that for the specific description of the statistical information, etc., reference can be made to the method embodiments shown above (such as the method shown in Figure 3, Figure 4 or Figure 6), which will not be described in detail here.

[0230] In some other embodiments of the present application, the communication device can be used to execute the actions performed by the terminal device in the above method embodiments. In this case, the communication device can be a terminal device, or the communication device can be or can be configured as a component of the terminal device (such as a chip or system, etc.), the transceiver unit 802 is used to execute the transceiver-related operations of the terminal device in the above method embodiments, and the processing unit 801 is used to execute the terminal device processing-related operations in the above method embodiments.

[0231] Exemplarily, the transceiver unit 802 is configured to send a message for registering for the CS voice service and receive a response message.

[0232] Optionally, the transceiver unit 802 is further configured to send a message for indicating the voice service of the IMS, and receive a message for rejecting registration of the voice service of the IMS.

[0233] It is understandable that for specific descriptions of the message for registering the CS voice service, the response message, the message for indicating the IMS voice service, the message for rejecting the registration of the IMS voice service, etc., reference can be made to the method embodiments shown above (such as the methods shown in Figures 3, 4, and 6), and will not be described in detail here.

[0234] In some other embodiments of the present application, the communication device can be used to execute the actions performed by the session management network element in the above method embodiment. In this case, the communication device can be a session management network element, or the communication device can be or be configured as a component of the session management network element (such as a chip or system, etc.), the transceiver unit 802 is used to execute the operations related to the transmission and reception of the session management network element in the above method embodiment, and the processing unit 801 is used to execute the operations related to the processing of the session management network element in the above method embodiment.

[0235] Illustratively, the transceiver unit 802 is configured to receive statistical information; the processing unit 801 is configured to determine that the voice service of the IMS is unavailable based on the statistical information; and the transceiver unit 802 is further configured to send information indicating that the voice service of the IMS is unavailable.

[0236] It is understandable that the specific description of the statistical information and the information indicating that the voice service of the IMS is unavailable can refer to the method embodiments shown above (such as the methods shown in Figures 3, 4, and 6), which will not be described in detail here.

[0237] Optionally, the above-mentioned communication device may further include a storage unit, which may be used to store instructions and / or data. The processing unit 801 may read the instructions and / or data in the storage unit so that the communication device implements the above-mentioned method embodiment.

[0238] It can be understood that the specific description of the transceiver unit and the processing unit shown in the embodiment of the present application is only an example. For the specific functions or execution steps of the transceiver unit and the processing unit, please refer to the above-mentioned method embodiment and will not be described in detail here.

[0239] The above describes the communication device according to the embodiment of the present application. The following describes possible product forms of the communication device. It should be understood that any product having the functions of the communication device described in FIG8 falls within the scope of protection of the embodiment of the present application. It should also be understood that the following description is merely illustrative and does not limit the product forms of the communication device according to the embodiment of the present application to these examples.

[0240] In one possible implementation, in the communication device shown in FIG8 , the processing unit 801 may be one or more processors, the transceiver unit 802 may be a transceiver, or the transceiver unit 802 may be a transmitting unit and a receiving unit, the transmitting unit may be a transmitter, the receiving unit may be a receiver, and the transmitting unit and the receiving unit are integrated into a single device, such as a transceiver. In the embodiment of the present application, the processor and the transceiver may be coupled, etc., and the embodiment of the present application does not limit the connection method between the processor and the transceiver. During the execution of the above method, the process of sending information in the above method can be understood as the process of the processor outputting the above information. When outputting the above information, the processor outputs the above information to the transceiver so that the transceiver can transmit it. After being output by the processor, the above information may also need to undergo other processing before reaching the transceiver. Similarly, the process of receiving information in the above method can be understood as the process of the processor receiving the input information. When the processor receives the input information, the transceiver receives the above information and inputs it into the processor. Furthermore, after the transceiver receives the above information, the above information may need to be processed further before being received by the processor.

[0241] As shown in FIG. 9 , the communication device 90 includes one or more processors 920 and a transceiver 910 .

[0242] In some embodiments of the present application, the communication device may be used to execute the steps or functions performed by the mobility management network element in the above method embodiments.

[0243] Illustratively, the transceiver 910 is configured to receive a message for registering for the CS voice service; and the processor 920 is configured to send a response message via the transceiver 910 when the CS voice service is unavailable.

[0244] Optionally, the transceiver 910 is further configured to receive information indicating that the voice service of the IMS is unavailable.

[0245] Optionally, the transceiver 910 is further configured to receive a message indicating a voice service of the IMS, and send a message for rejecting registration of the voice service of the IMS.

[0246] Optionally, the processor 920 is further configured to determine that the CS voice service is unavailable based on a voice service registration success rate corresponding to the MSC.

[0247] In other embodiments of the present application, the communication device can be used to execute the steps or functions performed by the user plane network element in the above method embodiments.

[0248] Exemplarily, the processor 920 is configured to obtain statistical information of signaling messages between the terminal device and the SBC in the IMS; and the transceiver 910 is configured to send the statistical information.

[0249] In some other embodiments of the present application, the communication device can be used to execute the steps or functions performed by the terminal device in the above method embodiments.

[0250] Exemplarily, the transceiver 910 is configured to send a message for registering for the CS voice service and receive a response message.

[0251] Optionally, the transceiver 910 is further configured to send a message indicating the voice service of the IMS, and receive a message for rejecting registration for the voice service of the IMS.

[0252] In some further embodiments of the present application, the communication device may be used to execute the steps or functions performed by the session management network element in the above method embodiments.

[0253] Exemplarily, the transceiver 910 is configured to receive statistical information; the processor 920 is configured to determine that the voice service of the IMS is unavailable based on the statistical information; and the transceiver 910 is further configured to send information indicating that the voice service of the IMS is unavailable.

[0254] It will be understood that the specific descriptions of the transceiver and processor shown in the embodiments of the present application are merely examples. For the specific functions or execution steps of the transceiver and processor, reference may be made to the above-mentioned method embodiments, which will not be described in detail here.

[0255] In the above embodiments, the description of the message for indicating the CS voice service, the response message, the information for indicating that the IMS voice service is unavailable, the message for indicating the IMS voice service, the message for refusing to register for the IMS voice service, and the statistical information, etc., can also be referred to the introduction in the above method embodiment, and will not be described in detail here.

[0256] In various implementations of the communication device shown in FIG9 , the transceiver may include a receiver and a transmitter, wherein the receiver is configured to perform a receiving function (or operation) and the transmitter is configured to perform a transmitting function (or operation). The transceiver is configured to communicate with other devices / devices via a transmission medium.

[0257] Optionally, the communication device 90 may further include one or more memories 930 for storing program instructions and / or data, etc. The memory 930 is coupled to the processor 920. The coupling in the embodiment of the present application is an indirect coupling or communication connection between devices, units or modules, which can be electrical, mechanical or other forms, and is used for information exchange between devices, units or modules. The processor 920 may operate in conjunction with the memory 930. The processor 920 may execute program instructions stored in the memory 930. Optionally, at least one of the above-mentioned one or more memories may be included in the processor.

[0258] The specific connection medium between the transceiver 910, processor 920, and memory 930 is not limited in the embodiments of the present application. In Figure 9, the memory 930, processor 920, and transceiver 910 are connected via a bus 940. The bus is represented by a bold line in Figure 9. The connection methods between other components are only for illustrative purposes and are not limiting. The bus can be divided into an address bus, a data bus, a control bus, etc. For ease of illustration, Figure 9 only uses a single bold line, but this does not mean that there is only one bus or only one type of bus.

[0259] In the embodiments of the present application, the processor may be a general-purpose processor, a digital signal processor, an application-specific integrated circuit, a field programmable gate array or other programmable logic device, a discrete gate or transistor logic device, a discrete hardware component, etc., and may implement or execute the various methods, steps, and logic block diagrams disclosed in the embodiments of the present application. The general-purpose processor may be a microprocessor or any conventional processor, etc. The steps of the methods disclosed in the embodiments of the present application may be directly implemented as being executed by a hardware processor, or may be executed by a combination of hardware and software modules in the processor, etc.

[0260] In the embodiment of the present application, memory may include but is not limited to non-volatile memories such as hard disk drive (HDD) or solid-state drive (SSD), random access memory (RAM), erasable programmable read-only memory (EPROM), read-only memory (ROM) or portable read-only memory (CD-ROM), etc. Memory is any storage medium that can be used to carry or store program code in the form of instructions or data structures, and can be read and / or written by a computer (such as the communication device shown in the present application), but is not limited thereto. The memory in the embodiment of the present application can also be a circuit or other arbitrarily capable of realizing a storage function, for storing program instructions and / or data.

[0261] Illustratively, the processor 920 is primarily used to process communication protocols and communication data, control the entire communication device, execute software programs, and process software program data. The memory 930 is primarily used to store software programs and data. The transceiver 910 may include a control circuit and an antenna. The control circuit is primarily used to convert baseband signals into radio frequency signals and process radio frequency signals. The antenna is primarily used to transmit and receive radio frequency signals in the form of electromagnetic waves. Input / output devices, such as a touch screen, display, and keyboard, are primarily used to receive user input and output data to the user.

[0262] When the communication device is powered on, the processor 920 can read the software program in the memory 930, interpret and execute the instructions of the software program, and process the data of the software program. When data needs to be sent wirelessly, the processor 920 performs baseband processing on the data to be sent and outputs the baseband signal to the radio frequency circuit. The radio frequency circuit performs radio frequency processing on the baseband signal and then transmits the radio frequency signal to the outside in the form of electromagnetic waves through the antenna. When data is sent to the communication device, the radio frequency circuit receives the radio frequency signal through the antenna, converts the radio frequency signal into a baseband signal, and outputs the baseband signal to the processor 920. The processor 920 converts the baseband signal into data and processes the data.

[0263] In another implementation, the RF circuit and antenna may be provided independently of the processor performing baseband processing. For example, in a distributed scenario, the RF circuit and antenna may be remotely arranged independent of the communication device.

[0264] It is understood that the communication device shown in the embodiment of the present application may also have more components than those in Figure 9, and the embodiment of the present application is not limited to this. The method performed by the processor and transceiver shown above is only an example. For the specific steps performed by the processor and transceiver, please refer to the method described above.

[0265] In another possible implementation, in the communication device shown in FIG8 , the processing unit 801 may be one or more logic circuits, and the transceiver unit 802 may be an input / output interface, or may be called a communication interface, or an interface circuit, or an interface, etc. Alternatively, the transceiver unit 802 may be a sending unit and a receiving unit, the sending unit may be an output interface, the receiving unit may be an input interface, and the sending unit and the receiving unit are integrated into one unit, such as an input / output interface. As shown in FIG10 , the communication device shown in FIG10 includes a logic circuit 1001 and an interface 1002. That is, the processing unit 801 may be implemented using a logic circuit 1001, and the transceiver unit 802 may be implemented using an interface 1002. The logic circuit 1001 may be a chip, a processing circuit, an integrated circuit, or a system on chip (SoC) chip, etc., and the interface 1002 may be a communication interface, an input / output interface, a pin, etc. For example, FIG10 is illustrated using the communication device as a chip, and the chip includes a logic circuit 1001 and an interface 1002.

[0266] In the embodiment of the present application, the logic circuit and the interface may also be coupled to each other. The embodiment of the present application does not limit the specific connection method between the logic circuit and the interface.

[0267] In some embodiments of the present application, the communication device can be used to execute the steps or functions performed by the mobility management network element in the above method embodiments. Exemplarily, interface 1002 is used to input a message for registering a CS voice service; logic circuit 1001 is used to output a response message through interface 1002 when the CS voice service is unavailable. Optionally, interface 1002 is also used to input information indicating that the IMS voice service is unavailable. Optionally, interface 1002 is also used to input a message indicating the IMS voice service, and output a message for rejecting registration for the IMS voice service. Optionally, logic circuit 1001 is also used to determine that the CS voice service is unavailable based on the voice service registration success rate corresponding to the MSC.

[0268] In other embodiments of the present application, the communication device can be used to execute the steps or functions performed by the user plane network element in the above method embodiments. For example, logic circuit 1001 is configured to obtain statistical information about signaling messages between a terminal device and an SBC in an IMS; and interface 1002 is configured to output the statistical information.

[0269] In yet other embodiments of the present application, the communication device can be used to execute the steps or functions performed by the terminal device in the above method embodiments. For example, interface 1002 is used to output a message for registering for a CS voice service and to input a response message. Optionally, interface 1002 is further used to output a message for instructing an IMS voice service and to input a message for rejecting registration for an IMS voice service.

[0270] In yet other embodiments of the present application, the communication device may be configured to execute the steps or functions performed by the session management network element in the above method embodiments. For example, interface 1002 is configured to input statistical information; logic circuit 1001 is configured to determine, based on the statistical information, that the IMS voice service is unavailable; and interface 1002 is further configured to output information indicating that the IMS voice service is unavailable.

[0271] It can be understood that the specific description of the logic circuit and interface shown in the embodiments of the present application is only an example. For the specific functions or execution steps of the logic circuit and interface, please refer to the above-mentioned method embodiment and will not be described in detail here.

[0272] In the above embodiments, the description of the message for indicating the CS voice service, the response message, the information for indicating that the IMS voice service is unavailable, the message for indicating the IMS voice service, the message for refusing to register for the IMS voice service, and the statistical information, etc., can also be referred to the introduction in the above method embodiment, and will not be described in detail here.

[0273] It can be understood that the communication device shown in the embodiment of the present application can implement the method provided in the embodiment of the present application in the form of hardware, or can implement the method provided in the embodiment of the present application in the form of software, etc., and the embodiment of the present application is not limited to this.

[0274] In addition, the present application also provides a computer program, which is used to implement the operations and / or processing performed by the terminal device in the method provided by the present application, or the operations and / or processing performed by the mobility management network element, or the operations and / or processing performed by the user plane network element, or the operations and / or processing performed by the session management network element.

[0275] The present application also provides a computer-readable storage medium, which stores computer code. When the computer code runs on a computer, the computer executes the operations and / or processing performed by the terminal device in the method provided by the present application, or the operations and / or processing performed by the mobility management network element, or the operations and / or processing performed by the user plane network element, or the operations and / or processing performed by the session management network element.

[0276] The present application also provides a computer program product, which includes computer code or computer program. When the computer code or computer program runs on a computer, the operations and / or processing performed by the terminal device in the method provided by the present application are executed, or the operations and / or processing performed by the mobility management network element are executed, or the operations and / or processing performed by the user plane network element are executed, or the operations and / or processing performed by the session management network element are executed.

[0277] In the several embodiments provided in this application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, or can be electrical, mechanical or other forms of connection.

[0278] The units described as separate components may or may not be physically separate, and 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 network units. Some or all of the units may be selected according to actual needs to achieve the technical effects of the solutions provided in the embodiments of the present application.

[0279] In addition, the functional units in the various embodiments of the present application may be integrated into a single processing unit, or each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0280] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a readable storage medium, including a number of instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned readable storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0281] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A communication method, characterized in that: The method comprises: The mobility management network element receives a message from a terminal device for registering a circuit switched CS voice service; When the CS voice service is unavailable, the mobility management network element sends a response message to the terminal device, where the response message is used to indicate that the terminal device resides in the first network, which provides data services for the terminal device.

2. The method according to claim 1, characterized in that The first network provides a voice service based on the CS voice or Internet Protocol IP Multimedia Subsystem IMS, and the mobility management network element sends a response message to the terminal device when the CS voice service is unavailable, including: When the CS voice service is unavailable and the voice service of the IMS is unavailable, the mobility management network element sends the response message to the terminal device.

3. The method according to claim 2, characterized in that The method further comprises: The mobility management network element receives information indicating that the voice service of the IMS is unavailable from the session management network element.

4. The method according to claim 3, characterized in that The information indicating that the voice service of the IMS is unavailable includes statistical information of signaling messages between the terminal device and a session border controller SBC in the IMS, and the statistical information is used to determine whether the voice service of the IMS is available.

5. The method according to claim 2 or 3, characterized in that The method further comprises: The session management network element receives statistical information from a user plane network element, where the statistical information is statistical information of signaling messages between the terminal device and a session border controller (SBC) in the IMS, and the statistical information is used to determine whether a voice service of the IMS is available; The session management network element determines that the voice service of the IMS is unavailable based on the statistical information.

6. The method according to claim 5, characterized in that The statistical information is a success rate of voice registration requests or voice call requests corresponding to at least one SBC address, and the session management network element determines that the voice service of the IMS is unavailable based on the statistical information, including: The session management network element determines that the voice service of the IMS is unavailable when the success rate of the voice registration request or the voice call request corresponding to the at least one SBC address is less than a first threshold.

7. The method according to any one of claims 2 to 6, characterized in that: The response message includes information indicating that the voice service of the IMS is unavailable.

8. The method according to any one of claims 2 to 7, characterized in that: The method further comprises: The mobility management network element receives a message from the terminal device for registering a voice service of the IMS; The mobility management network element sends a message for rejecting registration of the voice service of the IMS to the terminal device.

9. The method according to any one of claims 1 to 8, characterized in that The method further comprises: The mobility management network element determines that the CS voice service is unavailable based on a voice service registration success rate corresponding to a mobile switching center MSC.

10. The method according to any one of claims 1 to 9, characterized in that The method further comprises: The mobility management network element receives a message from the terminal device for requesting network attachment; The mobility management network element sends a message for accepting the network attachment to the terminal device.

11. A communication method, characterized in that: The method comprises: The terminal device sends a message to the mobility management network element for registering the circuit switched CS voice service; The terminal device receives a response message from the mobility management network element, where the response message is used to indicate that the terminal device resides in a first network, which provides data services for the terminal device, and the response message includes information indicating that the voice service of the Internet Protocol IP Multimedia Subsystem IMS is unavailable.

12. The method according to claim 11, characterized in that The method further comprises: The terminal device sends a message for registering the voice service of the IMS to the mobility management network element; The terminal device receives a message from the mobility management network element for rejecting registration of the voice service of the IMS.

13. A communication system, characterized in that: The communication system comprises: The session management network element is configured to send information indicating that the voice service of the Internet Protocol IP Multimedia Subsystem IMS is unavailable to the mobility management network element; A mobility management network element is configured to receive a message from a terminal device for registering a circuit-switched CS voice service, and to send a response message to the terminal device when the CS voice service is unavailable and the voice service of the IMS is unavailable, wherein the response message is used to indicate that the terminal device resides in a first network, and the first network provides data services for the terminal device.

14. The system according to claim 13, wherein: The information indicating that the voice service of the IMS is unavailable includes statistical information of signaling messages between the terminal device and a session border controller SBC in the IMS, and the statistical information is used to determine whether the voice service of the IMS is available.

15. The system according to claim 13, wherein: The system further includes a user plane network element; The user plane network element is configured to send statistical information to the session management network element, where the statistical information is statistical information of signaling messages between the terminal device and the session border controller (SBC) in the IMS, and the statistical information is used to determine whether the voice service of the IMS is available; The session management network element is further configured to determine, based on the statistical information, that the voice service of the IMS is unavailable.

16. The system according to claim 15, wherein: The statistical information is a success rate of voice registration requests or voice call requests corresponding to at least one SBC address, and the session management network element is specifically used to determine that the voice service of the IMS is unavailable when the success rate of the voice registration requests or voice call requests corresponding to the at least one SBC address is less than a first threshold.

17. The system according to any one of claims 13 to 16, characterized in that: The response message includes information indicating that the voice service of the IMS is unavailable.

18. The system according to any one of claims 13 to 17, characterized in that: The mobility management network element is further configured to determine that the CS voice service is unavailable based on a voice service registration success rate corresponding to a mobile switching center MSC.

19. A communication device, characterized in that: The method comprises a unit for executing the method according to any one of claims 1 to 12.

20. A computer-readable storage medium, characterized in that The computer-readable storage medium is used to store a computer program. When the computer program is executed, the method according to any one of claims 1 to 12 is performed.

21. A computer program, characterized in that When the computer program is executed, the method according to any one of claims 1 to 12 is performed.

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