Apparatus, method and computer program

Abstract

An apparatus, method and computer program are provided for determining an identifier serving a user equipment for a registered access and mobility management function associated with an Internet Protocol Multimedia Subsystem (IMS) service, while the user equipment may also have other registrations for the same subscription, but is not associated with an Internet Protocol Multimedia Subsystem (IMS) service.

Description

Technical Field

[0001] Various examples of the subject disclosure generally relate to apparatus, methods and computer programs, and more particularly (but not exclusively) to apparatus, methods and computer programs for apparatus. Background Art

[0002] A communication system can be viewed as a facility that enables communication sessions between two or more entities (eg, communication devices, base stations, and / or other nodes) by providing a bearer between the entities involved in the communication path.

[0003] The communication system may be a wireless communication system. Examples of wireless systems include public land mobile networks (PLMNs) operating based on radio standards, such as those provided by 3GPP, satellite-based communication systems, and different wireless local networks, such as wireless local area networks (WLANs). Wireless systems can typically be divided into cells, and are therefore often referred to as cellular systems.

[0004] Communication systems and associated equipment usually operate according to a given standard or specification, which specifies what the various entities associated with the system are allowed to do and how it should be achieved. Communication protocols and / or parameters that should be used for the connection are usually also defined therein. Examples include the so-called 5G standards. Summary of the invention

[0005] Some examples of the subject disclosure are described for certain aspects. These aspects are not intended to indicate the key or essential features of each example of the subject disclosure, nor are they intended to be used to limit its scope. In view of the subject disclosure, other features, aspects, and units will be readily apparent to those skilled in the art.

[0006] According to a first aspect, a device is provided, comprising means for performing the following operations: receiving a first registration request for registering a user equipment that the first access and mobility management function is to serve from a first access and mobility management function, the first registration request comprising a first registration identifier; receiving information indicating that the registration corresponding to the first registration request is associated with an Internet Protocol Multimedia Subsystem (IMS) service; receiving a request for information related to the IMS service from a network entity; determining a registration identifier and an access and mobility management function for the related IMS service; obtaining the information for the related IMS service from the determined access and mobility management function by providing the determined registration identifier to the determined access and mobility management function; and providing the requested information to the network entity.

[0007] Receiving information indicating that the registration corresponding to the first registration request is associated with an IMS service may include means for receiving a second registration request for the user equipment, the second registration request including the first registration identifier and information indicating that the packet data unit session is for an IMS service.

[0008] Receiving information indicating that the registration corresponding to the first registration request is associated with an IMS service may include means for receiving the second registration request from a session management function, the second registration request including information for registering that the session management function is to service a packet data unit session for the user equipment, the second registration request including the first registration identifier and information indicating that the packet data unit session is for the IMS service.

[0009] The apparatus may further include means for storing, for the user equipment, an association between the related IMS service and the received information indicating that the registration corresponding to the first registration request is associated with the IMS service.

[0010] The apparatus may further comprise means for identifying the first access and mobility management function in response to the request for information by retrieving the stored association.

[0011] The information indicating that the session is for an IMS service may include an indication that the session is for an IMS service.

[0012] The information indicating that the session is for an IMS service may include a data network name and / or a network slice identifier that can be used for the IMS service.

[0013] The means for receiving information indicating that the registration corresponding to the first registration request is associated with an IMS service may include means for receiving, in the first registration request, information indicating that the registration corresponding to the first registration request is associated with an IMS service.

[0014] The information indicating that the session is for an IMS service may include an indication that the session is for an IMS service.

[0015] The network entity may be configured to operate as a Home Subscriber System or an application server.

[0016] The means for obtaining may include means for signalling a request for information associated with the first registration identifier to the first access and mobility management function, and receiving the requested information associated with the first registration identifier from the first access and mobility management function.

[0017] The information associated with the first registration identifier may include at least one of: a last active time of the user equipment for the registration corresponding to the first registration request; a last active access type used by the user equipment for the registration corresponding to the first registration request; or an indication of whether IMS voice over packet switched sessions is supported in the area where the user equipment is registered for the registration corresponding to the first registration request.

[0018] According to a second aspect, a device is provided, comprising a component for performing the following operations: providing a first registration request for registering a user equipment to be served by an access and mobility management function to a unified data management function, the first registration request comprising a first registration identifier, wherein the device is included in the access and mobility management function.

[0019] The first registration request may include information indicating that the registration identifier is associated with an Internet Protocol Multimedia Subsystem (IMS) service.

[0020] The apparatus may further include a component for performing at least one of the following: receiving information from the user equipment indicating that the first registration request is associated with registration of the user equipment to a core network for an Internet Protocol Multimedia Subsystem (IMS) service; or determining that the first registration request is associated with the IMS service based on a packet data unit session established for the user equipment for a data network name and / or a network slice identifier corresponding to the Internet Protocol Multimedia Subsystem (IMS) service.

[0021] The information indicating that the session is for an IMS service may include an indication that the session is for an IMS service, wherein the indication is based on the information received from the user equipment.

[0022] The apparatus may further include means for receiving a request from the unified data management function for information associated with the first registration identifier; and signaling the requested information associated with the first registration identifier to the unified data management function.

[0023] The information associated with the first registration identifier may include at least one of: a last activity time of the user equipment for the registration corresponding to the first registration request; a last active access type used by the user equipment for the registration corresponding to the first registration request; or an indication of whether IMS voice over packet switched sessions is supported in the area in which the user equipment is registered for the registration corresponding to the first registration request.

[0024] The apparatus may further comprise means for providing the first registration identifier to a session management function in a packet data unit session establishment or modification request.

[0025] According to a third aspect, a device is provided, comprising a component for performing the following operations: providing a second registration request for registering that the session management function is to serve a packet data unit session for a user equipment to a unified data management function, the second registration request comprising a first registration identifier, wherein the second registration request comprises information indicating that the packet data unit session is associated with an Internet Protocol Multimedia Subsystem (IMS) service, wherein the device is included in the session management function.

[0026] The apparatus may comprise means for receiving the first registration identifier in a packet data unit session establishment or modification request from an access and mobility management function that is to serve the user equipment.

[0027] The information indicating that the session is for an IMS service may include an indication that the session is for an IMS service.

[0028] The information indicating that the session is for an IMS service may include a data network name and / or a network slice identifier that can be used for the IMS service.

[0029] According to a fourth aspect, a device is provided, comprising a component for performing the following operations: sending information to an access and mobility management function indicating that a first registration is associated with a registration of the user equipment to a core network for an Internet Protocol Multimedia Subsystem (IMS) service, wherein the device is included in the user equipment.

[0030] According to the fifth aspect, a device is provided, comprising: at least one processor; and at least one memory, the memory comprising code, which, when executed by the at least one processor, causes the device to perform: receiving a first registration request from a first access and mobility management function for registering a user equipment that the first access and mobility management function is to serve, the first registration request comprising a first registration identifier; receiving information indicating that the registration corresponding to the first registration request is associated with an Internet Protocol Multimedia Subsystem (IMS) service; receiving a request for information related to the IMS service from a network entity; determining a registration identifier and an access and mobility management function for the related IMS service; obtaining the information for the related IMS service from the determined access and mobility management function by providing the determined registration identifier to the determined access and mobility management function; and providing the requested information to the network entity.

[0031] Receiving information indicating that the registration corresponding to the first registration request is associated with an IMS service may include receiving a second registration request for the user equipment, the second registration request including the first registration identifier and information indicating that the packet data unit session is for an IMS service.

[0032] Receiving information indicating that the registration corresponding to the first registration request is associated with the IMS service may include: receiving the second registration request from a session management function, the second registration request including information for registering that the session management function is to serve a packet data unit session for the user equipment, the second registration request including the first registration identifier and information indicating that the packet data unit session is for the IMS service.

[0033] The apparatus may be further caused to perform: storing, for the user equipment, an association between the related IMS service and the received information indicating that the registration corresponding to the first registration request is associated with the IMS service.

[0034] The apparatus may be further caused to perform: identifying the first access and mobility management function in response to the request for information by retrieving the stored association.

[0035] The information indicating that the session is for an IMS service may include an indication that the session is for an IMS service.

[0036] The information indicating that the session is for an IMS service may include a data network name and / or a network slice identifier that can be used for the IMS service.

[0037] Receiving information indicating that the registration corresponding to the first registration request is associated with an IMS service may include receiving information in the first registration request indicating that the registration corresponding to the first registration request is associated with an IMS service.

[0038] The information indicating that the session is for an IMS service may include an indication that the session is for an IMS service.

[0039] The network entity may be configured to operate as a Home Subscriber System or an application server.

[0040] The obtaining may include signaling a request for information associated with the first registration identifier to the first access and mobility management function; and receiving the requested information associated with the first registration identifier from the first access and mobility management function.

[0041] The information associated with the first registration identifier may include at least one of: a last activity time of the user equipment for the registration corresponding to the first registration request; a last active access type used by the user equipment for the registration corresponding to the first registration request; or an indication of whether IMS voice over packet switched sessions is supported in the area in which the user equipment is registered for the registration corresponding to the first registration request.

[0042] According to the sixth aspect, a device is provided, comprising: at least one processor; and at least one memory, the memory comprising code, which, when executed by the at least one processor, causes the device to perform: providing a first registration request for registering a user equipment to be served by an access and mobility management function to a unified data management function, the first registration request comprising a first registration identifier, wherein the device is included in the access and mobility management function.

[0043] The first registration request may include information indicating that the registration identifier is associated with an Internet Protocol Multimedia Subsystem (IMS) service.

[0044] The apparatus may be further prompted to perform at least one of the following: receiving information from the user equipment indicating that the first registration request is associated with registration of the user equipment to a core network for an Internet Protocol Multimedia Subsystem (IMS) service; or determining that the first registration request is associated with the IMS service based on a packet data unit session established for the user equipment for a data network name and / or a network slice identifier corresponding to the Internet Protocol Multimedia Subsystem IMS service.

[0045] The information indicating that the session is for an IMS service may include an indication that the session is for an IMS service, wherein the indication is based on the information received from the user equipment.

[0046] The apparatus may be further caused to perform: receiving a request for information associated with the first registration identifier from the unified data management function; and signaling the requested information associated with the first registration identifier to the unified data management function.

[0047] The information associated with the first registration identifier may include at least one of: a last activity time of the user equipment for the registration corresponding to the first registration request; a last active access type used by the user equipment for the registration corresponding to the first registration request; or an indication of whether IMS voice over packet switched sessions is supported in the area in which the user equipment is registered for the registration corresponding to the first registration request.

[0048] The apparatus may be further caused to perform: providing the first registration identifier to a session management function in a packet data unit session establishment or modification request.

[0049] According to a seventh aspect, a device is provided, comprising: at least one processor; and at least one memory, the memory comprising code, which, when executed by the at least one processor, causes the device to perform: providing a second registration request to a unified data management function for registering a packet data unit session that the session management function is to serve for a user device, the second registration request comprising a first registration identifier, wherein the second registration request comprises information indicating that the packet data unit session is associated with an Internet Protocol Multimedia Subsystem (IMS) service, wherein the device is included in the session management function.

[0050] The apparatus may be further caused to perform: receiving, in a packet data unit session establishment or modification request, the first registration identifier from an access and mobility management function that is to serve the user equipment.

[0051] The information indicating that the session is for an IMS service may include an indication that the session is for an IMS service.

[0052] The information indicating that the session is for an IMS service may include a data network name and / or a network slice identifier that can be used for the IMS service.

[0053] According to an eighth aspect, a device is provided, comprising: at least one processor; and at least one memory, the memory comprising code, which, when executed by the at least one processor, causes the device to perform: sending information to an access and mobility management function indicating that a first registration is associated with a registration of the user equipment to a core network for an Internet Protocol Multimedia Subsystem (IMS) service, wherein the device is included in the user equipment.

[0054] According to a ninth aspect, a method for an apparatus is provided, the method comprising: receiving from a first access and mobility management function a first registration request for registering that the first access and mobility management function will serve a user equipment, the first registration request comprising a first registration identifier; receiving information indicating that the registration corresponding to the first registration request is associated with an Internet Protocol Multimedia Subsystem (IMS) service; receiving from a network entity a request for information related to the IMS service; determining a registration identifier and an access and mobility management function for the related IMS service; obtaining the information for the related IMS service from the determined access and mobility management function by providing the determined registration identifier to the determined access and mobility management function; and providing the requested information to the network entity.

[0055] Receiving information indicating that the registration corresponding to the first registration request is associated with an IMS service may include receiving a second registration request for the user equipment, the second registration request including the first registration identifier and information indicating that the packet data unit session is for an IMS service.

[0056] Receiving information indicating that the registration corresponding to the first registration request is associated with the IMS service may include: receiving the second registration request from a session management function, the second registration request including information for registering that the session management function is to serve a packet data unit session for the user equipment, the second registration request including the first registration identifier and information indicating that the packet data unit session is for the IMS service.

[0057] The method may further comprise storing, for the user equipment, an association between the related IMS service and the received information indicating that the registration corresponding to the first registration request is associated with the IMS service.

[0058] The method may further comprise identifying the first access and mobility management function in response to the request for information by retrieving the stored association.

[0059] The information indicating that the session is for an IMS service may include an indication that the session is for an IMS service.

[0060] The information indicating that the session is for an IMS service may include a data network name and / or a network slice identifier that can be used for the IMS service.

[0061] Receiving information indicating that the registration corresponding to the first registration request is associated with an IMS service may include receiving information in the first registration request indicating that the registration corresponding to the first registration request is associated with an IMS service.

[0062] The information indicating that the session is for an IMS service may include an indication that the session is for an IMS service.

[0063] The network entity may be configured to operate as a Home Subscriber System or an application server.

[0064] The obtaining may include signaling a request for information associated with the first registration identifier to the first access and mobility management function; and receiving the requested information associated with the first registration identifier from the first access and mobility management function.

[0065] The information associated with the first registration identifier may include at least one of: a last activity time of the user equipment for the registration corresponding to the first registration request; a last active access type used by the user equipment for the registration corresponding to the first registration request; or an indication of whether IMS voice over packet switched sessions is supported in the area in which the user equipment is registered for the registration corresponding to the first registration request.

[0066] According to the tenth aspect, a method for a device is provided, the method comprising: providing a first registration request for registering a user equipment to be served by an access and mobility management function to a unified data management function, the first registration request comprising a first registration identifier, wherein the device is included in the access and mobility management function.

[0067] The first registration request may include information indicating that the registration identifier is associated with an Internet Protocol Multimedia Subsystem (IMS) service.

[0068] The method may further include at least one of the following: receiving information from the user equipment indicating that the first registration request is associated with registration of the user equipment to a core network for an Internet Protocol Multimedia Subsystem (IMS) service; or determining that the first registration request is associated with the IMS service based on a packet data unit session established for the user equipment for a data network name and / or a network slice identifier corresponding to the Internet Protocol Multimedia Subsystem IMS service.

[0069] The information indicating that the session is for an IMS service may include an indication that the session is for an IMS service, wherein the indication is based on the information received from the user equipment.

[0070] The method may further include receiving a request from the unified data management function for information associated with the first registration identifier; and signaling the requested information associated with the first registration identifier to the unified data management function.

[0071] The information associated with the first registration identifier may include at least one of: a last activity time of the user equipment for the registration corresponding to the first registration request; a last active access type used by the user equipment for the registration corresponding to the first registration request; or an indication of whether IMS voice over packet switched sessions is supported in the area in which the user equipment is registered for the registration corresponding to the first registration request.

[0072] The method may further comprise providing the first registration identifier to a session management function in a packet data unit session establishment or modification request.

[0073] According to an eleventh aspect, a method for an apparatus is provided, the method comprising: providing a second registration request to a unified data management function for registering a packet data unit session that the session management function is to serve for a user equipment, the second registration request comprising a first registration identifier, wherein the second registration request comprises information indicating that the packet data unit session is associated with an Internet Protocol Multimedia Subsystem (IMS) service, wherein the apparatus is included in the session management function.

[0074] The method may further comprise receiving the first registration identifier in a packet data unit session establishment or modification request from an access and mobility management function that is to serve the user equipment.

[0075] The information indicating that the session is for an IMS service may include an indication that the session is for an IMS service.

[0076] The information indicating that the session is for an IMS service may include a data network name and / or a network slice identifier that can be used for the IMS service.

[0077] According to a twelfth aspect, a method for an apparatus is provided, the method comprising: sending information to an access and mobility management function indicating that a first registration is associated with a registration of the user equipment to a core network for an Internet Protocol Multimedia Subsystem (IMS) service, wherein the apparatus is included in the user equipment.

[0078] According to the thirteenth aspect, a device is provided, comprising: a receiving circuit for receiving a first registration request for registering a user equipment that the first access and mobility management function is to serve from a first access and mobility management function, the first registration request comprising a first registration identifier; a receiving circuit for receiving information indicating that the registration corresponding to the first registration request is associated with an Internet Protocol Multimedia Subsystem (IMS) service; a receiving circuit for receiving a request for information related to the IMS service from a network entity; determining a registration identifier and an access and mobility management function for the related IMS service; an obtaining circuit for obtaining the information for the related IMS service from the determined access and mobility management function by providing the determined registration identifier to the determined access and mobility management function; and a providing circuit for providing the requested information to the network entity.

[0079] The receiving circuitry for receiving information indicating that the registration corresponding to the first registration request is associated with an IMS service may include receiving circuitry for receiving a second registration request for the user equipment, the second registration request including the first registration identifier and information indicating that a packet data unit session is for an IMS service.

[0080] The receiving circuit for receiving information indicating that the registration corresponding to the first registration request is associated with an IMS service may include: a receiving circuit for receiving the second registration request from a session management function, the second registration request including information for registering that the session management function is to serve a packet data unit session for the user equipment, the second registration request including the first registration identifier and information indicating that the packet data unit session is for the IMS service.

[0081] The apparatus may further comprise storage circuitry for storing, for the user equipment, an association between the related IMS service and the received information indicating that the registration corresponding to the first registration request is associated with the IMS service.

[0082] The apparatus may further comprise identification circuitry for identifying the first access and mobility management function in response to the request for information by retrieving the stored association.

[0083] The information indicating that the session is for an IMS service may include an indication that the session is for an IMS service.

[0084] The information indicating that the session is for an IMS service may include a data network name and / or a network slice identifier that can be used for the IMS service.

[0085] The receiving circuitry for receiving information indicating that the registration corresponding to the first registration request is associated with an IMS service may include receiving circuitry for receiving information indicating that the registration corresponding to the first registration request is associated with an IMS service in the first registration request.

[0086] The information indicating that the session is for an IMS service may include an indication that the session is for an IMS service.

[0087] The network entity may be configured to operate as a Home Subscriber System or an application server.

[0088] The obtaining circuit for obtaining may include: a signaling circuit for signaling a request for information associated with the first registration identifier to the first access and mobility management function; and a receiving circuit for receiving the requested information associated with the first registration identifier from the first access and mobility management function.

[0089] The information associated with the first registration identifier may include at least one of: a last activity time of the user equipment for the registration corresponding to the first registration request; a last active access type used by the user equipment for the registration corresponding to the first registration request; or an indication of whether IMS voice over packet switched sessions is supported in the area in which the user equipment is registered for the registration corresponding to the first registration request.

[0090] According to the fourteenth aspect, a device is provided, comprising: a providing circuit for providing a first registration request for registering a user equipment to be served by an access and mobility management function to a unified data management function, the first registration request comprising a first registration identifier, wherein the device is included in the access and mobility management function.

[0091] The first registration request may include information indicating that the registration identifier is associated with an Internet Protocol Multimedia Subsystem (IMS) service.

[0092] The apparatus may further include at least one of: a receiving circuit for receiving information from the user equipment indicating that the first registration request is associated with registration of the user equipment to a core network for an Internet Protocol Multimedia Subsystem (IMS) service; or a determining circuit for determining that the first registration request is associated with the IMS service based on a packet data unit session established for the user equipment corresponding to a data network name and / or a network slice identifier for the Internet Protocol Multimedia Subsystem IMS service.

[0093] The information indicating that the session is for an IMS service may include an indication that the session is for an IMS service, wherein the indication is based on the information received from the user equipment.

[0094] The apparatus may further include receiving circuitry for receiving a request for information associated with the first registration identifier from the unified data management function and signaling circuitry for signaling the requested information associated with the first registration identifier to the unified data management function.

[0095] The information associated with the first registration identifier may include at least one of: a last activity time of the user equipment for the registration corresponding to the first registration request; a last active access type used by the user equipment for the registration corresponding to the first registration request; or an indication of whether IMS voice over packet switched sessions is supported in the area in which the user equipment is registered for the registration corresponding to the first registration request.

[0096] The apparatus may further comprise a providing circuit for providing the first registration identifier to a session management function in a packet data unit session establishment or modification request.

[0097] According to the fifteenth aspect, a device is provided, comprising: a providing circuit for providing a second registration request to a unified data management function for registering a packet data unit session that the session management function is to serve for a user equipment, the second registration request comprising a first registration identifier, wherein the second registration request comprises information indicating that the packet data unit session is associated with an Internet Protocol Multimedia Subsystem (IMS) service, wherein the device is included in the session management function.

[0098] The apparatus may include a receiving circuit for receiving the first registration identifier in a packet data unit session establishment or modification request from an access and mobility management function that is to serve the user equipment.

[0099] The information indicating that the session is for an IMS service may include an indication that the session is for an IMS service.

[0100] The information indicating that the session is for an IMS service may include a data network name and / or a network slice identifier that can be used for the IMS service.

[0101] According to the sixteenth aspect, a device is provided, comprising: a sending circuit for sending information to an access and mobility management function indicating that a first registration is associated with a registration of the user equipment to a core network for an Internet Protocol Multimedia Subsystem (IMS) service, wherein the device is included in the user equipment.

[0102] According to the seventeenth aspect, a non-temporary computer-readable medium comprising program instructions is provided, wherein the program instructions cause the device to execute: receiving a first registration request for registering that the first access and mobility management function will serve a user equipment from a first access and mobility management function, the first registration request comprising a first registration identifier; receiving information indicating that the registration corresponding to the first registration request is associated with an Internet Protocol Multimedia Subsystem (IMS) service; receiving a request for information related to the IMS service from a network entity; determining a registration identifier and an access and mobility management function for the related IMS service; obtaining the information for the related IMS service from the determined access and mobility management function by providing the determined registration identifier to the determined access and mobility management function; and providing the requested information to the network entity.

[0103] Receiving information indicating that the registration corresponding to the first registration request is associated with an IMS service may include receiving a second registration request for the user equipment, the second registration request including the first registration identifier and information indicating that the packet data unit session is for an IMS service.

[0104] Receiving information indicating that the registration corresponding to the first registration request is associated with the IMS service may include: receiving the second registration request from a session management function, the second registration request including information for registering that the session management function is to serve a packet data unit session for the user equipment, the second registration request including the first registration identifier and information indicating that the packet data unit session is for the IMS service.

[0105] The apparatus may be further caused to perform: storing, for the user equipment, an association between the related IMS service and the received information indicating that the registration corresponding to the first registration request is associated with the IMS service.

[0106] The apparatus may be further caused to perform: identifying the first access and mobility management function in response to the request for information by retrieving the stored association.

[0107] The information indicating that the session is for an IMS service may include an indication that the session is for an IMS service.

[0108] The information indicating that the session is for an IMS service may include a data network name and / or a network slice identifier that can be used for the IMS service.

[0109] Receiving information indicating that the registration corresponding to the first registration request is associated with an IMS service may include receiving information in the first registration request indicating that the registration corresponding to the first registration request is associated with an IMS service.

[0110] The information indicating that the session is for an IMS service may include an indication that the session is for an IMS service.

[0111] The network entity may be configured to operate as a Home Subscriber System or an application server.

[0112] The obtaining may include signaling a request for information associated with the first registration identifier to the first access and mobility management function; and receiving the requested information associated with the first registration identifier from the first access and mobility management function.

[0113] The information associated with the first registration identifier may include at least one of: a last activity time of the user equipment for the registration corresponding to the first registration request; a last active access type used by the user equipment for the registration corresponding to the first registration request; or an indication of whether IMS voice over packet switched sessions is supported in the area in which the user equipment is registered for the registration corresponding to the first registration request.

[0114] According to the eighteenth aspect, a device is provided, comprising: at least one processor; and at least one memory, wherein the memory comprises a non-temporary computer-readable medium comprising program instructions, wherein the program instructions cause the device to execute: providing a first registration request for registering an access and mobility management function to serve a user equipment to a unified data management function, wherein the first registration request comprises a first registration identifier, wherein the device is included in the access and mobility management function.

[0115] The first registration request may include information indicating that the registration identifier is associated with an Internet Protocol Multimedia Subsystem (IMS) service.

[0116] The apparatus may be further prompted to perform at least one of the following: receiving information from the user equipment indicating that the first registration request is associated with registration of the user equipment to a core network for an Internet Protocol Multimedia Subsystem (IMS) service; or determining that the first registration request is associated with the IMS service based on a packet data unit session established for the user equipment for a data network name and / or a network slice identifier corresponding to the Internet Protocol Multimedia Subsystem IMS service.

[0117] The information indicating that the session is for an IMS service may include an indication that the session is for an IMS service, wherein the indication is based on the information received from the user equipment.

[0118] The apparatus may be further caused to perform: receiving a request for information associated with the first registration identifier from the unified data management function; and signaling the requested information associated with the first registration identifier to the unified data management function.

[0119] The information associated with the first registration identifier may include at least one of: a last activity time of the user equipment for the registration corresponding to the first registration request; a last active access type used by the user equipment for the registration corresponding to the first registration request; or an indication of whether IMS voice over packet switched sessions is supported in the area in which the user equipment is registered for the registration corresponding to the first registration request.

[0120] The apparatus may be further caused to perform: providing the first registration identifier to a session management function in a packet data unit session establishment or modification request.

[0121] According to the nineteenth aspect, a non-transitory computer-readable medium comprising program instructions is provided, wherein the program instructions cause an apparatus to execute: providing a second registration request to a unified data management function for registering a packet data unit session that the session management function is to serve for a user device, the second registration request comprising a first registration identifier, wherein the second registration request comprises information indicating that the packet data unit session is associated with an Internet Protocol Multimedia Subsystem (IMS) service, wherein the apparatus is included in the session management function.

[0122] The apparatus may be further caused to perform: receiving the first registration identifier in a packet data unit session establishment or modification request from an access and mobility management function that is to serve the user equipment.

[0123] The information indicating that the session is for an IMS service may include an indication that the session is for an IMS service.

[0124] The information indicating that the session is for an IMS service may include a data network name and / or a network slice identifier that can be used for the IMS service.

[0125] According to the twentieth aspect, a non-transitory computer-readable medium comprising program instructions is provided, wherein the program instructions cause an apparatus to execute: sending information to an access and mobility management function indicating that a first registration is associated with a registration of the user equipment to a core network for an Internet Protocol Multimedia Subsystem (IMS) service, wherein the apparatus is included in the user equipment.

[0126] According to a twenty-first aspect, there is provided a computer program product stored on a medium, which can cause an apparatus to perform any of the methods described herein.

[0127] According to a twenty-second aspect, an electronic device is provided, which may include the apparatus described herein.

[0128] According to a twenty-third aspect, there is provided a chipset, which may include the apparatus described herein.

[0129] Many different aspects have been described above. It should be understood that further aspects may be provided by combining any two or more of the above aspects. BRIEF DESCRIPTION OF THE DRAWINGS

[0130] Some examples will now be described by way of illustration only with reference to the accompanying drawings, in which:

[0131] Figures 1A-1C An example representation of a 5G system is shown;

[0132] Figure 2 An example representation of a network device is shown;

[0133] Figure 3 An example representation of a user device is shown;

[0134] Figures 4 to 6 Example signaling is shown; and

[0135] Figures 7 to 10 Operations that may be performed by an example apparatus are illustrated. DETAILED DESCRIPTION

[0136] Various examples of the subject disclosure are further described. It should be understood that these examples are described for illustrative purposes and are to help those skilled in the art understand and implement the subject disclosure without implying any specific limitation on the scope of the subject disclosure. The examples described herein can be implemented in various ways except as described below.

[0137] The terms used herein are generally used to describe specific examples only and are not intended to be limiting. In the following description and claims, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this subject disclosure belongs, unless otherwise defined.

[0138] It should be understood that although the terms "first", "second", etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element without departing from the scope of the exemplary embodiments.

[0139] As used herein, “at least one of: ” and “at least one of ” and similar expressions, where a list of two or more elements is connected by “and” or “or”, mean at least any one element, or at least any two or more elements, or at least all elements.

[0140] As used herein, unless explicitly stated, performing a step “in response to A” does not mean that the step is performed immediately after “A” occurs, and may include one or more intermediate steps.

[0141] Described below are example operations that may be performed to enable (or otherwise facilitate) identifying which access registration to use for Internet Protocol Multimedia Subsystem (IMS) services.

[0142] For example, hereinbelow, a registry (e.g., a unified data management entity) is disclosed that uses a registration identifier to maintain an identity of an access and mobility management function (AMF) that is registered to manage access of a user equipment (UE) using IMS services through a specified access.

[0143] As described herein, this identification may be maintained and / or established in any of a number of different ways.

[0144] For example, when the UE registers with the AMF, the UE may send an indication to the AMF that the registration is for IMS services. In some examples, the indication may include a registration identifier. In some examples, both the AMF and the Session and Mobility Function (SMF) may register the same registration identifier at the UDM, where the SMF indicates that the session established by the SMF for the UE is for IMS services. In some examples, the AMF may send a registration identifier to the SMF for use by the SMF during registration at the UDM. The UDM may determine that the AMF has registered to manage access to UEs using IMS services by associating the received registration identifier and using an indication provided by the SMF to determine that the AMF is managing access to UEs using IMS services.

[0145] In some examples disclosed herein, there may be multiple SMFs serving a PDU session for a UE. The AMF may send a registration identifier to each of the multiple SMFs. In some examples, at least one of the multiple SMFs may send a registration identifier to the UDM. In other examples, each of the multiple SMFs may send a registration identifier to the UDM, but only one of the multiple SMFs may indicate that the registration is for an IMS service.

[0146] As another example disclosed herein, when the UE indicates to the AMF that a specific access is used to provide IMS services, the AMF may provide information directly to the UDM to register with the UDM indicating that the AMF is managing the access of the UE using the IMS service through the specific access. For example, the AMF may provide this information when the AMF registers with the UDM to manage the access of the UE.

[0147] The registry may later receive a request from the application server to determine whether the call can be provided using IMS services (i.e., the call can be terminated as Voice over Internet Protocol (VoIP) in IMS) or whether it needs to be broken out to the circuit switched domain. In response, the registry may query the AMF to determine whether the call can be provided using IMS services. In the event that there are two or more possible AMFs, the registry may determine which AMF to query based on information indicating that the AMF is managing access to the UE using IMS services. The registry may provide the requesting application server with further information about the connection that the AMF is providing to the UE. The application server may use the provided information to route the communication to the UE (e.g., to terminate the call at the UE).

[0148] In the following, certain examples will be explained with reference to devices that are generally capable of communicating via a wireless cellular system and a mobile communication system serving such mobile communication devices. For the sake of brevity and clarity, such examples will be described below with reference to a 5G wireless communication system. However, it should be understood that such examples are not limited to a 5G wireless communication system and may, for example, be applied to other wireless communication systems (e.g., in particular current 6G proposals, IEEE 802.11, etc.).

[0149] Before describing the examples in detail, we will refer to Figures 1A to 3 Briefly explain some aspects of 5G wireless communication systems.

[0150] Figure 1A An example representation of a 5G system (5GS) 100 is shown. The 5GS may include a user equipment (UE) 102 (which may also be referred to as a communication device or terminal), a 5G access network (AN) (which may be a 5G radio access network (RAN) or any other type of 5G AN, such as a non-3GPP interworking function (N3IWF) / trusted non-3GPP gateway function (TNGF) for non-trusted / trusted non-3GPP access or a wired access gateway function (W-AGF) (for wired access) 104, a 5G core (5GC) 106, one or more application functions (AFs) 108, and one or more data networks (DNs) 110. The UE may subscribe to receive at least one service from the AF. To help facilitate user traffic to efficiently deliver services to the UE, the network may classify user traffic (e.g., Internet Protocol (IP) flows) into different service data flows (SDFs) with different quality of service (QoS) classes based on the type of service provided through the SDF. Different QoS rules may be applied to each SDF.

[0151] A 5G RAN may include one or more gNodeB (gNB) distributed unit functions connected to one or more gNodeB (gNB) unit functions. A RAN may include one or more access nodes.

[0152] 5GC 106 may include one or more access and mobility management functions (AMF) 112, one or more session management functions (SMF) 114, one or more authentication server functions (AUSF) 116, one or more unified data management (UDM) functions 118, one or more user plane functions (UPF) 120, one or more unified data repository (UDR) functions 122, one or more network repository functions (NRF) 128, and / or one or more network open functions (NEF) 124. The role of NEF is to provide a secure opening of network services (e.g., voice, data connections, billing, subscriber data, etc.) to third parties. Although NRF 128 is not depicted as having its interface, it is understood that this is for clarity and that NRF 128 may have multiple interfaces with other network functions.

[0153] 5GC 106 also includes a network data analysis function (NWDAF) 126. NWDAF is responsible for providing network analysis information on requests from one or more network functions or devices within the network. Network functions can also subscribe to NWDAF 126 to receive information from it. Accordingly, NWDAF 126 is also configured to receive and store network information from one or more network functions or devices within the network. Data collection by NWDAF 126 can be performed based on at least one subscription to an event provided by at least one network function.

[0154] about Figure 1B Another example network configuration is shown.

[0155] Figure 1B A first UE 101 ' is shown connected to a Call Session Control Function (CSCF) 102' via an undefined network 103'.

[0156] The CSCF 102' is connected to a terminating access domain selection (T-ADS) function 104', which is capable of selecting a circuit switched (CS) access and / or one or more packet switched (PS) access networks to be used for transporting a called session of the UE 101'. The functionality of the T-ADS function is further discussed in 3GPP TS 23.221, 23.292, 23.237, 29.503 and 29.518.

[0157] The T-ADS function 104' is connected to a Home Subscriber Server (HSS) and a Unified Data Management 105', which in turn is connected to an Access and Mobility Management Function (AMF) 106'. The HSS / UDM maintains user profile information for registered subscribers, which can be used to authenticate and authorize those registered subscribers. The AMF 106' interfaces with a Session Management Function (SMF) and / or a User Plane Function (UPF) 107' and a gNB 108' operating according to a New Radio based protocol. The SMF / UPF 107' also interfaces with the CSCF 102'. The SMF / UPF 107' and the gNB 108' may be included in the same entity (e.g., an apparatus including at least one processor and at least one memory, the memory including code that, when executed by the at least one processor, causes the apparatus to perform the functions of a gNB and an SMF / UPF). The SMF / UPF 107' and the gNB 108' may be included in different entities (e.g., in different respective apparatuses).

[0158] The CSCF 102' further interacts with an enhanced mobile satellite service (eMSS) 109', which in turn interacts with a base station control (BSC) of a radio network controller (RNC) 110'. The BSC-RNC 110' interacts with an access node 111'. The access node 111' operates according to a Global System for Mobile Communications (GSM) / Universal Mobile Telecommunications System (UMTS) network and is shown signaling to a UE 112'.

[0159] 3GPP defines an architectural framework for delivering multimedia services (such as voice, video, audio, etc.) over Internet Protocol (IP) networks. This architectural framework is called IP Multimedia Subsystem (IMS) and is related to Figure 1C To be shown.

[0160] Figure 1CA network is shown, comprising: an application layer including an application server 101", a control layer including an HSS102", a CSCF103", a media resource function (MRF) 104" and a signaling gateway (SGW) / media gateway control function (MGCF) (SGW / MGCF) 105", and a transport layer including an IP network 106", a gateway 107" and a public switched telephone network (PSTN) 108". The IP network 106" interacts with a UE 109". The application server 101" interacts with the CSCF 103" and the MRF 104". The CSCF 103" interacts with the HSS102", the MRF 104" and the SGW / MGCF 105". The SGW / MGCF 105" provides interoperability with circuit switched networks, such as the PSTN 108", by interacting with the gateway 107", which then interacts with the PSTN 108".

[0161] Under current schemes, any single given UE may be registered with a unified data management (UDM) entity in the core network, with a single 3GPP access registration and a single non-3GPP access registration.

[0162] For a called call (e.g., a call-based operation that ends and / or terminates at the UE), the IMS AS queries the UDM and / or HSS to request information for selecting the called domain (e.g., the called Public Land Mobile Network (PLMN) on which the UE is based). Based on where the UE that is the subject of the called call is attached to the network, the UDM and / or HSS provides the requesting IMS AS with NR, non-3GPP, LTE and / or CS access details. Based on this information, the IMS AS may attempt to terminate the IMS call in the domain to which the user is attached. In the event that the IMS AS is provided with multiple different accesses to the UE, the IMS AS may attempt to terminate the IMS call sequentially in each access until the call is successfully terminated at the UE.

[0163] Figure 2An example of a control device for a communication system is shown, for example coupled to and / or used to control: a station of an access system (such as a RAN node, such as a base station, gNB), a central unit of a cloud architecture or a node of a core network (such as an AMF or UPF), a scheduling entity such as a spectrum management entity, or a server or host, such as a device hosting an NRF, NWDAF, AMF, SMF, UDM / UDR, etc. The control device may be integrated with a node or module of a core network or RAN or external to it. In some examples, the base station includes a separate control device unit or module. In other examples, the control device may be another network element, such as a radio network controller or a spectrum controller. The control device 200 may be arranged to provide control of communications in a service area of ​​the system. The device 200 includes at least one memory 201, at least one data processing unit 202, 203 and an input / output interface 204. Through the interface, the control device may be coupled to a receiver and a transmitter of the device. The receiver and / or the transmitter may be implemented as a radio front end or a remote radio head. For example, the control device 200 or the memory 201 may be configured to execute appropriate software code to provide control functions. References herein to "code" are understood to refer to software code, and vice versa.

[0164] Now refer to Figure 3 describing in greater detail an example wireless communication device, Figure 3 A schematic partial cross-sectional view of a communication device 300 is shown. Such a communication device is generally referred to as a user equipment (UE) or a terminal. Any device capable of sending and receiving radio signals can provide a suitable mobile communication device. Some examples include a mobile station (MS) or a mobile device (e.g., a mobile phone or a so-called "smart phone"), a computer equipped with a wireless interface card or other wireless interface facilities (e.g., a USB dongle), a personal data assistant (PDA) or a tablet computer equipped with wireless communication capabilities, or a virtual reality device, an augmented reality device, a mixed reality device or other extended reality (e.g., a virtual reality headset), or any combination of these devices or similar devices. The mobile communication device can provide, for example, communication of data for carrying communications such as voice, e-mail (email), text messages, multimedia and extended reality media. Therefore, a variety of services can be supplied and provided to users through their communication devices. Some examples of these services include two-way or multi-way calls, data communications or multimedia services or simply access to a data communication network system, such as the Internet. Broadcast or multicast data can also be provided to users. Some examples of content include downloads, television and radio programs, videos, advertisements, various warnings and other information.

[0165] A wireless communication device may be, for example, a mobile device, i.e., a device that is not fixed to a particular location, or may be a stationary device. A wireless device may or may not communicate using human interaction. As described herein, the term UE or "user" (more informally) may be used to refer to any type of wireless communication device.

[0166] The wireless device 300 may receive signals via the air or radio interface 307 by appropriate means for receiving and may transmit signals by appropriate means for transmitting radio signals. Figure 3 In the wireless device, the transceiver device is schematically represented by block 306. The transceiver device 306 may be provided, for example, by a radio component and an associated antenna arrangement. The antenna arrangement may be configured internally or externally to the wireless device.

[0167] The wireless device is typically equipped with at least one data processing entity 301, at least one memory 302 and other possible components 303 for software code and hardware assistance to perform the tasks it is designed to perform, including controlling access to and communications with access systems and other communication devices. The data processing, storage and other related control devices may be provided in appropriate circuit boards and / or chipsets. This feature is indicated by the mark 304. The user can control the operation of the wireless device through a suitable user interface such as a keyboard 305, voice commands, a touch screen or touch pad, a combination thereof, etc. A display or virtual reality headset / glasses 308, speakers and microphones may also be provided. In addition, the wireless communication device may include appropriate connectors (wired and / or wireless) to connect to other devices and / or for connecting external accessories (such as hands-free devices) to the wireless communication device.

[0168] 3GPP has released multiple releases (Rel) to define operational communication protocols related to communication networks. Currently, goals and work are being set for Release 18 (Rel. 18) and Rel. 19.

[0169] For example, a study item for Rel.19 has been released to study upper layer service steering, switching and segmentation for dual 3GPP access.

[0170] This study set several different objectives.

[0171] For example, one objective is to study additional use cases and potential service requirements that could benefit from 5GS supporting upper layer steering, splitting and handover of UE traffic (e.g., belonging to the same data session) across two 3GPP access links, assuming there is only a single subscription to the administrative domain (e.g., a single subscription to a PLMN). This may include at least the cases where there is a single subscription to a single PLMN, a PLMN plus a separate non-public network (NPN), and / or two PLMNs.

[0172] The UE may also access network services using multiple accesses (e.g., multiple access types of the same or different 3GPP radio access technologies). For example, these may be two radio access technologies, including New Radio (NR) plus one of NR, Non-Terrestrial Network (NTN), or LTE, or including NTN plus one of NR, NTN, or LTE. In this example, NTN may be associated with NR-based satellite access, including satellites operating in different orbits (e.g., Geosynchronous Equatorial Orbit (GEO), Medium Earth Orbit (MEO), and / or Low Earth Orbit (LEO)).

[0173] Another objective involves providing a case for two management domain scenarios (eg PLMN plus PLMN or NPN scenarios), where the two domains may be managed by the same operator or by different operators with a service agreement between them.

[0174] The study also aims to consider simultaneous connections via dual 3GPP access, assuming the UE supports appropriate radio capabilities (e.g., dual radio).

[0175] To help facilitate coordination of multi-network scenarios, the T-ADS function may provide T-ADS information between various network elements. The T-ADS information involves information elements that indicate the type of radio access serving the UE and further indicate whether IMS voice over packet-switched sessions are supported in the current routing area and / or tracking area associated with the UE. The application server may obtain T-ADS information about a user and / or UE from the HSS and / or UDM using a "read" operation.

[0176] For example, 3GPP TS29.328 describes operations that an application server may use to retrieve information from an HSS. For example, an application server may signal a T-ADS request to the HSS. Upon receiving the T-ADS request from the application server, the HSS may check whether a service node (e.g., a serving general packet radio service (GPRS) support node (SGSN) and / or a mobility management entity (MME) node) is registered for the user on the HSS.

[0177] Typically, if the service node is not registered, a response may be returned to the application server indicating that IMS voice over PS sessions are not supported. UE activity time and last RAT type are not reported.

[0178] If all service nodes are registered (e.g., both the MME and SGSN are registered), a response indicating that IMS voice over PS sessions are supported may be returned to the application server. The response may include an indication of a response from the MME or SGSN (whichever reported the most recent UE activity time) to indicate the most recent UE activity time, and the last RAT type is also reported.

[0179] In some examples, the response may include an indication that it is not known whether IMS Voice over PS session is supported. Further details of these procedures are discussed in 3GPP TS 29.328.

[0180] During an IMS called call, an IMS server (e.g., a Service Centralization and Continuity Application Server (SCC AS)) requests T-ADS information of a user equipment from an HSS. In response to the request, the HSS may obtain the T-ADS information from the UDM. For example, the HSS may forward the request to the UDM. In some examples, the HSS and the UDM may be the same entity or different entities. However, when multiple registrations are available in the UDM, it is unclear how the UDM and / or the HSS determine which access network is more suitable for the called call.

[0181] Furthermore, even if the HSS and / or UDM can determine the "best" access network to provide details to the requesting SCC AS, it is unclear how the SCC AS can terminate calls to multiple accesses.

[0182]

[0013] In the following and as described herein, a mechanism for addressing at least one of the above issues is provided.

[0183] As part of these mechanisms, each UE registration may have (e.g., be assigned) a specific registration identifier that is provided to the UDM for registration. The registration identifier may identify the UE's registration for 5GC. For example, for a first registration in which the UE registers with the AMF for 5GC access over RAN1, the first registration may have a first registration identifier, and for a second registration in which the UE registers with the AMF for 5GC access over RAN2, the second registration may have a second registration identifier, and so on. The UDM may use this registration identifier in a variety of ways to identify the AMF that provides IMS access to the UE.

[0184] For example, consider the case where AMF and SMF provide information that UDM can use to identify AMF.

[0185] Typically, the Nudm_UECM_Registration service operation is used by a NF (e.g., by any of AMF, SMF, etc.) to register at the UDM as a NF serving a UE (e.g., AMF) or a NF serving a PDU session (e.g., SMF).

[0186] For example, AMF can register as a serving NF for access and mobility management services for UE using Nudm_UECM_Registration message during registration. Further, SMF can register as a serving NF for session management services using Nudm_UECM_Registration message during PDU session establishment.

[0187] The NF calling the Nudm_UECM_Registration service operation may provide multiple identifiers to the UDM for registration, including a NF identifier (which uniquely identifies the NF), a NF type identifier (which uniquely identifies the type of the NF), and an identifier of the UE (e.g., a global identifier, such as a subscriber identifier of the UE). The UDM authorizes the request, and if the request is accepted, the NF is registered in the UDM as a NF serving the UE.

[0188] According to the subject disclosure, the AMF associates the registration identifier with the registration of the AMF at the UDM for the UE and may provide the registration identifier to the SMF when the AMF is establishing a session on behalf of the user equipment (e.g., when establishing a PDU session during a PDU session establishment procedure). The SMF may subsequently provide the registration identifier to the UDM during the SMF registration procedure (e.g., using the Nudm_UECM_Registration service operation).

[0189] Further, during the PDU session registration process, the SMF may provide an indication to the UDM during the registration process that the PDU session or the SMF registration is to be used for IMS. When the SMF does not provide an indication to the UDM, the UDM may derive the information from other information provided to the UDM during IMS PDU session establishment (e.g., Data Network Name (DNN) and / or Single Network Slice Selection Assistance Information (S-NSSAI)). The UDM may identify which AMF is to be used for IMS by associating registration identifiers received in different operations and by using information included in the SMF registration request identifying that the registration identifier is to be used for IMS.

[0190] For example, a first registration request may be provided from a network function (eg, SMF and / or AMF) including information indicating that a registration identifier for the UE is associated with an IMS service.

[0191] When a request for information about which AMF serves the UE for IMS is later received by the UDM from the application server via the HSS (e.g. when the UDM subsequently receives a T-ADS query via the HSS), the UDM selects the AMF registration with a registration identifier that matches the registration identifier received in the SMF registration for the identified IMS PDU session. Information associated with that AMF registration may be selected for use in responding to the request for information. For example, information may be provided about which access was last used by the UE for that AMF registration and when that access was last used by the UE.

[0192] As an alternative example, instead of the SMF providing an indication of IMS provisioning, the AMF may directly signal information instructing the AMF to provide appropriate access to IMS to the UE as part of the AMF's registration information.

[0193] about Figures 4 to 10 These features are shown.

[0194] Figure 4 Example signaling that may be performed in a first scenario where a UE has multiple registrations to the same access network through different AMFs is shown.

[0195] Figure 4 The signaling that can be performed between UE 401, first AMF 402, second AMF 403, SMF 404, UDM / HSS 405 and application server (AS) 406 is shown. The application server may include an IMS AS. The application server may include an SCC AS.

[0196] During 4001, the UE 401 and the first AMF 402 exchange signaling for enabling (or otherwise causing) the UE to attach to a first radio access network associated with the first AMF 402 and / or to attach to the first AMF 402. The signaling may contain a first registration identifier.

[0197] During 4002, the first AMF 402 signals the UDM / HSS 405. The signaling may include a first registration identifier. The first registration identifier may identify the registration of the UE to the 5GC through the first radio access network. The signaling may include a Nudm_UECM_Registration message.

[0198] During 4003, the UE 401 and the second AMF 403 exchange signaling for enabling (or otherwise causing) the UE to attach to a second radio access network associated with the second AMF 403 and / or to the second AMF 403. The signaling may include a second registration identifier. The UE 401 and / or the second AMF 403 may determine (e.g., identify to other entities) that the registration of 4003 is for IMS registration during this process.

[0199] During 4004, the second AMF 403 signals the UDM / HSS 405. The signaling may include a second registration identifier. The signaling may be provided using, for example, a Nudm_UECM_Registration message.

[0200] During 4005, the UE 401 signals the second AMF 403. The signaling may relate to initiating a session (e.g. initiating an IMS PDU session).

[0201] During 4006, the second AMF 403 signals the SMF 404. The signaling may include a PDU session related request. The PDU session related request may involve establishing a PDU session targeting an IMS service. The signaling of 4006 may include a second registration identifier. For example, the second AMF 403 may signal the second registration identifier to the SMF 404 regardless of the DNN of the PDU session.

[0202] During 4007, SMF 404 signals UDM / HSS 405. The signaling may include a second registration identifier. The signaling may include an indication that the PDU session and / or SMF is being registered for an IMS session. The signaling of 4007 may include a Nudm_UECM_Registration message. In other words, for example, SMF 404 may perform session registration at UDM / HSS and provide at least a second registration identifier.

[0203] During 4008, the UDM / HSS 405 stores the second registration identifier with an indication that the session associated with the registration identifier is for an IMS service. This may be performed by storing the second registration identifier and the indication at the UDR. In the event that no indication is provided during 4007 that the PDU session and / or SMF is being registered for IMS, the UDM / HSS 405 may infer that the registration is for an IMS session using a combination of the DNN and slice information (e.g., S-NSSAI) associated with the SMF registration.

[0204] During 4009 , the application server 406 receives an indication of an incoming called call for the UE 401 .

[0205] During 4010, the application server 406 signals the UDM / HSS 405. The signaling may include a request for T-ADS information related to the UE.

[0206] In some examples, the signaling may request at least one of the following:

[0207] - the time of the last radio contact of the UE for the corresponding registration identifier;

[0208] - for the corresponding registration identifier, whether IMS voice over PS sessions are supported in the registration area in which the UE is currently registered;

[0209] - for the corresponding registration identifier, an indication of whether IMS voice over PS sessions over non-3GPP access are supported in the wireless local area network (WLAN) with which the UE is currently registered; or

[0210] - For the corresponding registration identifier, the current access type and radio access technology (RAT type).

[0211] The signaling may include, for example, Sh data read operations (e.g., Sh PULL and / or NhssimsSubscriberDataManagement_Get operations, see GPP TS29.328 and 3GPP TS29.562). As an example, Sh-PULL is a process used between an application server and an HSS and is called by the AS to read data for a specific user from the HSS. It should therefore be understood that any operation or protocol that can be used by an application server to obtain information about a user and / or UE of a UE may be used during 4010 or in a similar function (e.g., during Figure 5 and / or Figure 6 was used during the period

[0212] During 4011, the UDM selects an AMF registration with a registration identifier matching the registration identifier received in the SMF registration for the IMS PDU session and uses that AMF registration for T-ADS purposes.

[0213] During 4012, the UDM / HSS 405 selects the AMF associated with the selected AMF registration of 4011 and sends a query to the second AMF 403 to obtain the last activity time of the UE. The query may include, for example, a Namf_MT_ProvideDomainSelectionInfo request service operation (see, for example, 3GPP TS 23.502 and TS 29.518). If necessary, the UDM / HSS 405 may be configured to contact the HSS or MME to determine information related to other access details. The UDM / HSS 405 may then provide a consolidated response to the application server 406, which includes information for allowing the application server 406 to cause the call to be terminated to the selected access / registration.

[0214] Figure 5 An example scenario involving provision of T-ADS information when there are multiple registrations for the same access at the same AMF is shown.

[0215] Figure 5 Signaling is shown that may be performed between a UE 501, a first AMF 502, an SMF 503, a UDM / HSS 504, and an application server (AF) 505. The application server may include an IMS AS. The application server may include an SCC AS.

[0216] During 5001, the UE 501 and the first AMF 502 exchange signaling for enabling (or otherwise causing) the UE to attach to a first radio access network associated with the first AMF 502 and / or to attach to the first AMF 502. The signaling may contain a first registration identifier.

[0217] During 5002, the first AMF 502 signals the UDM / HSS 504. The signaling may include a first registration identifier. The first registration identifier may identify a combination of the UE 501 and the first radio access network. The signaling may include a Nudm_UECM_Registration message.

[0218] During 5003, the UE 501 and the first AMF 502 exchange signaling for enabling (or otherwise causing) the UE to make another attachment to a second radio access network associated with the first AMF 502. The signaling may include a second registration identifier. The UE 501 and / or the first AMF 502 may determine (e.g. identify to other entities) that the registration of 5003 is for IMS registration during this process.

[0219] During 5004, the first AMF 502 signals the UDM / HSS 504. The signaling may include a second registration identifier. The second registration identifier may identify a combination of the UE 501 and the second radio access network. The signaling may include a Nudm_UECM_Registration message.

[0220] During 5005, the UE 501 signals the first AMF 502. The signaling may involve initiating a session (e.g., an IMS PDU session).

[0221] During 5006, the first AMF 502 signals the SMF 503. The signaling may include a PDU session related request. The PDU session related request may relate to establishing a PDU session for an IMS service. The signaling of 5006 may include a second registration identifier. For example, the first AMF 502 may signal the second registration identifier to the SMF 503 regardless of the DNN of the PDU session.

[0222] During 5007, the SMF 503 signals the UDM / HSS 504. The signaling may include a second registration identifier. The signaling may include an indication that the PDU session and / or the SMF is being registered for the IMS session. The signaling of 5007 may include a Nudm_UECM_Registration message. In other words, for example, the SMF 503 may perform session registration at the UDM / HSS and provide at least a second registration identifier.

[0223] During 5008, the UDM / HSS 504 stores the second registration identifier with an indication that the session associated with the registration identifier is for an IMS service. This may be performed by storing the second registration identifier and the indication at the UDR. In the event that no indication is provided during 5007 that the PDU session and / or SMF is being registered for IMS, the UDM / HSS 504 may infer that the registration is for an IMS session using a combination of the DNN and slice information (e.g., S-NSSAI) associated with the SMF registration.

[0224] During 5009 , the application server 505 receives an indication of an incoming called call for the UE 501 .

[0225] During 5010, the application server 505 signals the UDM / HSS 504. The signaling may include a request for T-ADS information related to the UE. The signaling may include, for example, an Sh data read operation (e.g., Sh PULL and / or NhssimsSubscriberDataManagement_Get operations, see GPP TS29.328 and 3GPP TS29.562).

[0226] During 5011, the UDM selects an AMF registration with a registration identifier matching the registration identifier received in the SMF registration for the IMS PDU session and uses that AMF registration for T-ADS purposes.

[0227] During 5012, the UDM / HSS 504 signals the first AMF 502. The signaling may request a "last activity time" for the second AMF / registration.

[0228] Since two registrations are maintained in the same AMF (first AMF 502), the UDM / HSS may inform the AMF of which registration the T-ADS information is being requested for by including a registration identifier (e.g., the second registration identifier in this example) in the signaling to the first AMF 502. The signaling of 5012 may be included in a provide domain selection information request (e.g., a Namf_MT_ProvideDomainSelectionInfo request (see 3GPP TS23.502 and 3GPP TS29.518)).

[0229] The signaling may request at least one of the following:

[0230] - the time of the last radio contact of the UE for the corresponding registration identifier;

[0231] - for the corresponding registration identifier, whether IMS voice over PS sessions are supported in the registration area in which the UE is currently registered;

[0232] - for the corresponding registration identifier, an indication of whether support for IMS voice over PS sessions over non-3GPP access is supported in the WLAN to which the UE is currently registered; or

[0233] - For the corresponding registration identifier, the current access type and RAT type.

[0234] Although not shown, the first AMF 502 may provide at least one of the above information requested during 5012. The AMF may choose to consider a registration in order to provide this information to the UDM as part of a Namf_MT_ProvideDomainSelectionInfo request to the T-ADS (e.g., a registration associated with the second registration identifier).

[0235] During 5013, the UDM / HSS 504 selects a first AMF and sends a query to the first AMF 502 to find out the last activity time of the UE. If necessary, the UDM / HSS 504 can be configured to contact the HSS or MME to determine information related to other access details. The UDM / HSS 504 can then provide a combined response to the application server 505, which includes information for allowing the application server 505 to cause the call to terminate to the selected access / registration.

[0236] Figure 6 An example scenario involving provision of T-ADS information when there are multiple registrations for the same access at the same AMF is shown.

[0237] Figure 6 Signaling is shown that may be performed between a UE 601, a first AMF 602, a UDM / HSS 603, and an application server (AF) 604. The application server may include an IMS AS. The application server may include an SCC AS.

[0238] During 6001, the UE 601 and the first AMF 602 exchange signaling for enabling (or otherwise causing) the UE to attach to a radio access network associated with the first AMF 602 and / or to attach to the first AMF 602. The signaling may include an indication from the UE that the registration is intended for IMS services.

[0239] During 6002, the first AMF 602 signals the UDM / HSS 603. The signaling may include a first registration identifier. The signaling may include an indication that the first registration identifier is to be used for the IMS. The signaling may include a Nudm_UECM_Registration message.

[0240] During 6003, the UE 601 and the first AMF 602 exchange signaling for enabling (or otherwise causing) the UE to attach to a second radio access network associated with the first AMF 602.

[0241] During 6004, the first AMF 602 signals the UDM / HSS 603. The signaling may include the second registration identifier. The signaling may include a Nudm_UECM_Registration message. The signaling may not include an indication that the second registration identifier is for IMS registration.

[0242] During 6005, UDM / HSS 603 stores the first registration identifier with an indication that the first registration identifier is associated with providing IMS services to UE 601. This may be performed by storing the first registration identifier and the indication in the UDR. UDM / HSS 603 stores the second registration identifier with an indication that the second registration identifier is not associated with providing IMS services to UE 601.

[0243] During 6006 , the application server 604 receives an indication of an incoming called call for the UE 601 .

[0244] During 6007, the application server 604 signals the UDM / HSS 603. The signaling may include a request for T-ADS information related to the UE. The signaling may include, for example, an Sh data read operation (e.g., Sh PULL and / or NhssimsSubscriberDataManagement_Get operations, see GPP TS29.328 and 3GPP TS29.562).

[0245] During 6008, the UDM selects an AMF registration with a registration identifier associated with the IMS provision (e.g., the first registration identifier, provided via signaling of 6001), and uses that AMF registration for T-ADS purposes (e.g., obtaining information related to the first registration identifier and returning it to the application server / HSS).

[0246] During 6009, the UDM / HSS 603 signals the first AMF 602. This signaling may request a "last activity time" for the second AMF / registration.

[0247] Since two registrations are maintained in the same AMF (first AMF 602), the UDM / HSS can inform the AMF for which registration the T-ADS information is being requested by including a registration identifier (e.g., the second registration identifier in this example) in the signaling to the first AMF 602. The signaling of 6009 may be included in a provide domain selection information request (e.g., Namf_MT_ProvideDomainSelectionInfo request (see 3GPP TS23.602 and 3GPP TS29.518)).

[0248] The signaling may request at least one of the following:

[0249] - the time of the last radio contact of the UE for the corresponding registration identifier;

[0250] - for the corresponding registration identifier, whether IMS voice over PS sessions are supported in the registration area in which the UE is currently registered;

[0251] - for the corresponding registration identifier, an indication of whether support for IMS voice over PS sessions over non-3GPP access is supported in the WLAN to which the UE is currently registered; or

[0252] - For the corresponding registration identifier, the current access type and RAT type.

[0253] Although not shown, the first AMF 602 may provide at least one of the above information requested during 6008. The AMF may choose to consider the registration in order to provide this information to the UDM as part of the Namf_MT_ProvideDomainSelectionInfo request to the T-ADS.

[0254] During 6010, the UDM / HSS 603 selects an AMF associated with the selected AMF registration of 6008 and sends a query to the first AMF 603 to obtain the last activity time of the UE. If necessary, the UDM / HSS 603 can be configured to contact the HSS or MME to determine information related to other access details. The UDM / HSS 603 can then be configured to provide a combined response including information for allowing the application server 604 to cause the call to be terminated to the selected access / registration.

[0255] As Figure 4 , Figure 5 and / or Figure 6 In a variation of any one of the examples, the AMF (403 / 502 / 602) may implicitly determine that the registration of the UE (401 / 501 / 601) is for access to the IMS service (e.g., the AMF may determine that the registration of the UE is for access to the IMS service without the UE signaling an indication that the registration is for access to the IMS service).

[0256] For example, the AMF may receive signaling associated with a PDU session toward a data network name (DNN) in association with a registration of the UE (401 / 501 / 601) (e.g., a non-access stratum (NAS) PDU session establishment request from the UE or inter-AMF mobility signaling) and / or single network slice selection assistance information (S-NSSAI) associated with an IMS service. The AMF may use the received information to determine that the associated registration is for the IMS service and signal the information to the UDM / HSS (405 / 504 / 603). The signaling from the AMF may include a registration identifier corresponding to a registration identifier associated with the UE via a specific access network node. The signaling from the AMF may include an indication that the registration identifier will be used to provide IMS services to the UE. The signaling may include a Nudm_UECM_Update message.

[0257] Figures 7 to 10 Operations that may be performed by the apparatus described herein are shown. These operations may correspond to the features described above with respect to the examples provided. It is to be understood that the above examples may be used to illustrate how the following features may be implemented in at least one environment, and that correspondence may be found between the functionality mentioned below and at least one feature of the above examples. It is further to be understood that Figures 7 to 10 Any feature having the same feature number as that in another figure may be a corresponding feature.

[0258] Figure 7 Operations that may be performed by an apparatus for a unified data management function are shown. The apparatus may be configured to operate as a unified data management function. For example, the apparatus may be configured to perform one or more functions of the unified data management function.

[0259] During 701, the apparatus receives a first registration request from a first access and mobility management function for registering that the first access and mobility management function will serve a user equipment, the first registration request including a first registration identifier.

[0260] The apparatus may receive another (second) registration request for registering that the first access and mobility function or the second access and mobility function will serve the user equipment, the second registration request including the second registration identifier. The apparatus may simultaneously maintain information about the first and second registrations (e.g., in parallel and / or simultaneously).

[0261] During 702, the device receives information indicating that a registration corresponding to a first registration request is associated with an Internet Protocol Multimedia Subsystem (IMS) service.

[0262] The apparatus receives a request for information related to an IMS service from a network entity during 703. The request may include a request for T-ADS information.

[0263] During 704, the apparatus determines a registration identifier for the relevant IMS service and access and mobility management functions.

[0264] During 705, the apparatus obtains said information for the associated IMS service from the determined access and mobility management function by providing the determined registration identifier to the determined access and mobility management function. The determined access and mobility management function may respond to the request including the determined registration identifier with the requested information.

[0265] During 706, the device provides the requested information (eg, obtained information) to the network entity.

[0266] in other words, Figure 7 The apparatus may determine, based on the received information and the received first registration request, a first access and mobility management function as an AMF providing IMS services for the user equipment, and provide an identifier of the first access and mobility to the network function based on the determination.

[0267] The apparatus may receive an indication indicating that a registration corresponding to the first registration request is associated with the IMS service by receiving a second registration request for the user equipment, the second registration request including the first registration identifier and information indicating that the packet data unit session is for the IMS service.

[0268] The apparatus may receive information indicating that a registration corresponding to the first registration request is associated with an IMS service by receiving a second registration request from a session management function, the second registration request including information for registering that the session management function will serve a packet data unit session for the user equipment, the second registration request including the first registration identifier and information indicating that the packet data unit session is for the IMS service.

[0269] The apparatus may store, for the user equipment, an association between the related IMS service and the received information indicating that the registration corresponding to the first registration request is associated with the IMS service.

[0270] The apparatus may identify the first access and mobility management function in response to the request for information by retrieving the stored association.

[0271] The information indicating that the session is for the IMS service may include an indication that the session is for the IMS service.

[0272] The information indicating that the session is for IMS service may include a data network name and / or a network slice identifier that can be used for IMS service. This information combination can be used to determine that the session associated with the data network name and / or network slice identifier is for IMS.

[0273] The apparatus may receive the information indicating that the registration corresponding to the first registration request is associated with the IMS service by receiving, in the first registration request, the information indicating that the registration corresponding to the first registration request is associated with the IMS service.

[0274] The apparatus may identify the first access and mobility management function in response to the request for information by retrieving the stored association.

[0275] The information indicating that the session is for the IMS service may include an indication that the session is for the IMS service.

[0276] The network entity may include a Home Subscriber System or an application server.

[0277] The apparatus may signal a request for information associated with a first registration identifier to a first access and mobility management function, and receive the requested information associated with the first registration identifier from the first access and mobility management function. The information associated with the first registration identifier may include at least one of: a last activity time of the user equipment for the registration corresponding to the first registration request; a last active access type used by the user equipment for the registration corresponding to the first registration request; or an indication of whether IMS voice over packet switched sessions are supported in an area where the user equipment is registered for the registration corresponding to the first registration request.

[0278] Figure 8 Operations that may be performed by an apparatus for access and mobility management functions are illustrated. The apparatus may be configured to operate as an access and mobility management function. For example, the apparatus may be configured to perform one or more functions of an access and mobility management function.

[0279] During 801, the apparatus provides a first registration request for registering that the access and mobility management function will serve a user equipment to the unified data management function, the first registration request comprising a first registration identifier.

[0280] The first registration request may include information indicating that the registration identifier is associated with an Internet Protocol Multimedia Subsystem (IMS) service.

[0281] The apparatus may receive information from the user equipment indicating that the first registration request is associated with registration of the user equipment with the core network for an Internet Protocol Multimedia Subsystem (IMS) service.

[0282] The device can determine that the first registration request is associated with an Internet Protocol Multimedia Subsystem (IMS) service based on a PDU session established for the user equipment for a data network name and / or a network slice identifier corresponding to the IMS service.

[0283] The information indicating that the session is for an IMS service may include an indication that the session is for an IMS service, wherein the indication is based on information received from the user equipment.

[0284] The device may receive a request for information associated with the first registration identifier from the unified data management function and signal the requested information associated with the first registration identifier to the unified data management function.

[0285] The information associated with the first registration identifier may include at least one of: a last activity time of the user equipment for the registration corresponding to the first registration request; a last active access type used by the user equipment for the registration corresponding to the first registration request; or an indication of whether IMS voice over packet switched sessions is supported in the area where the user equipment is registered for the registration corresponding to the first registration request.

[0286] The apparatus may provide the first registration identifier to the session management function in a packet data unit session establishment or modification request signaled to the session management function.

[0287] Fig. 9 Operations that may be performed by an apparatus for a session management function are shown. The apparatus may be configured to operate as a session management function. For example, the apparatus may be configured to perform one or more functions of a session management function.

[0288] During 901, the device provides a second registration request to the unified data management function for registering the session management function to use the service for a packet data unit session of the user equipment, the second registration request including the first registration identifier, wherein the second registration request includes information indicating that the packet data unit session is associated with an Internet Protocol Multimedia Subsystem (IMS) service.

[0289] The apparatus may receive the first registration identifier in a packet data unit session establishment or packet data unit session modification request from an access and mobility management function that will serve the user equipment.

[0290] The information indicating that the session is for the IMS service may include an indication that the session is for the IMS service.

[0291] The information indicating that the session is for an IMS service may include a data network name and / or a network slice identifier that can be used for the IMS service.

[0292] Fig.10 Operations that may be performed by an apparatus for a user equipment are shown. The apparatus may be included in the user equipment or implemented by the user equipment.

[0293] During 1001 , the apparatus sends information to an access and mobility management function indicating that a first registration is associated with a registration of a user equipment with a core network for an Internet Protocol Multimedia Subsystem (IMS) service.

[0294] It should be understood that references to various network functions (e.g., AMF, SMF, etc.) hereinabove may include devices that perform at least some of the functions associated with these network functions. In addition, a device configured to operate as a network function may include a virtual network function instance of the network function. Various examples have been described hereinabove using radio access architectures based on Long Term Evolution Advanced (LTE Advanced, LTE-A) or New Radio (NR, 5G) as examples of access architectures to which the described technology may be applied, however, the examples are not limited to such architectures. These examples may also be applied to other types of communication networks with suitable components by appropriately adjusting parameters and processes. Some examples of other options suitable for the system are Universal Mobile Telecommunications System (UMTS) Radio Access Network (UTRAN), Wireless Local Area Network (WLAN or Wi-Fi), Worldwide Interoperability for Microwave Access (WiMAX), Personal Communications Service (PCS), (ZigBee), Wideband Code Division Multiple Access (WCDMA), systems using Ultra-Wideband (UWB) technology, sensor networks, mobile ad hoc networks (MANETs) Internet Protocol Multimedia Subsystem (IMS), and anticipated 6G systems or any combination thereof.

[0295] As described herein, various examples are described in the detailed description. In general, some examples may be implemented in hardware or dedicated circuits, software code, logic, or any combination thereof. For example, some examples may be implemented in hardware, while other examples may be implemented in firmware or software code, which may be executed by a controller, microprocessor, or other computing device, but the examples are not limited thereto. Although various examples may be shown and described as block diagrams, flow charts, or illustrated and described using some other graphical representations, it is fully understood that the blocks, devices, systems, techniques, or methods described herein may be implemented as some examples in hardware, software code, firmware code, dedicated circuits or logic, general hardware or controllers or other computing devices, or some combination thereof.

[0296] The examples may be implemented by computer software code stored in a memory and executable by at least one data processor of the entity involved, or by hardware, or by a combination of software code and hardware.

[0297] The memory referred to herein may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory.

[0298] The (data) processor referred to herein may be of any type suitable for the local technical environment, and in some examples may include one or more of a general purpose computer, a special purpose computer, a microprocessor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), an FPGA, a gate level circuit, and a processor based on a multi-core processor architecture.

[0299] It should be further noted in this regard that any process (e.g. Figure 7 , and / or Figure 8 , and / or Fig. 9 , and / or Fig.10 The processes described in and / or otherwise herein) may represent the operation of a computer program deployed by at least one processor included in the device (where the computer program includes instructions for causing the device to perform at least one action, the instructions being represented as software code stored on at least one memory), or interconnected logic circuits, blocks and functions, or a combination of the operation of a computer program and logic circuits, blocks and functions deployed by at least one processor included in the device. The software code may be stored on a memory, such as a physical medium, such as a memory chip, or a memory block implemented within a processor, a magnetic medium (such as a hard disk or floppy disk), and an optical medium (such as a DVD and its data variants, a CD, etc.).

[0300] The memory may be of any type suitable for the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory, and removable memory. The data processor may be of any type suitable for the local technical environment and may include one or more of a general-purpose computer, a special-purpose computer, a microprocessor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a gate-level circuit, and a processor based on a multi-core processor architecture, as non-limiting examples.

[0301] Additionally or alternatively, some examples may be implemented using circuits. The circuits may be configured to perform one or more functions and / or method steps described previously. The circuits may be provided in a base station and / or a communication device and / or a core network entity.

[0302] As used herein, the term "circuitry" may refer to one or more or all of the following examples:

[0303] (a) pure hardware circuit implementation (e.g. implementation in analog and / or digital circuits only), and

[0304] (b) a combination of hardware circuitry and software code, such as (where applicable):

[0305] (i) a combination of analog and / or digital hardware circuitry and software / firmware code, and

[0306] (ii) a processor (including a digital signal processor) with software code, any portion of software code and memory that works together to enable an apparatus such as a communication device or base station to perform the various functions described above, and

[0307] (c) Circuits and / or processors (eg, a microprocessor or a portion of a microprocessor) that require software code (eg, firmware) for operation, but where the software code may not be present when it is not needed for operation.

[0308] This definition of circuitry applies to all uses of the term herein, including in any claims. As a further example, as used herein, the term circuitry also covers implementations of merely a hardware circuit or processor (or multiple processors) or a portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware code. The term circuitry also covers, for example, an integrated device.

[0309] Embodiments of the subject disclosure may be practiced in various components, such as integrated circuit modules. The design of integrated circuits is generally a highly automated process. Complex and powerful software tools are available to convert a logic level design into a semiconductor circuit design ready to be etched and formed on a semiconductor substrate.

[0310] The term "non-transitory" as used herein is a restriction on the medium itself (eg, tangible, as opposed to a signal), not on the persistence of data storage (eg, RAM versus ROM).

[0311] The scope of protection sought for various examples of the subject disclosure is set forth by the independent claims. Examples and features described herein that do not fall within the scope of the independent claims, if any, should be construed as helpful examples for understanding the subject disclosure.

[0312] The foregoing description provides a complete and informative description of example embodiments of the subject disclosure by way of non-limiting and illustrative examples. However, various modifications and adaptations may be apparent to those skilled in the relevant art when the foregoing description is read in conjunction with the accompanying drawings and claims. However, all such and similar modifications of the teachings of the subject disclosure will still fall within the scope of the examples described herein. In fact, there are further embodiments including combinations of one or more examples with any other examples described herein.

Claims

1. An apparatus comprising: receiving, from a first access and mobility management function, a first registration request for registering a user equipment to be served by the first access and mobility management function, the first registration request comprising a first registration identifier; receiving information indicating that the registration corresponding to the first registration request is associated with an Internet Protocol Multimedia Subsystem (IMS) service; receiving a request for information related to an IMS service from a network entity; Determine the registration identifiers and access and mobility management functions for the relevant IMS services; obtaining information for the associated IMS service from the determined access and mobility management function by providing the determined registration identifier to the determined access and mobility management function; as well as The requested information is provided to the network entity.

2. The device according to claim 1, wherein: Receiving information indicating that the registration corresponding to the first registration request is associated with an IMS service includes means for: A second registration request for the user equipment is received, the second registration request including the first registration identifier and information indicating that the packet data unit session is for an IMS service.

3. The device according to claim 2, wherein: Receiving information indicating that the registration corresponding to the first registration request is associated with an IMS service includes means for: The second registration request is received from a session management function, the second registration request comprising information for registering that the session management function is to serve a packet data unit session for the user equipment, the second registration request comprising the first registration identifier and information indicating that the packet data unit session is for an IMS service.

4. The device according to claim 3, wherein: The apparatus further comprises means for storing, for the user equipment, an association between the related IMS service and the received information indicating that the registration corresponding to the first registration request is associated with the IMS service.

5. The device according to claim 4, wherein: The apparatus comprises components for the following operations: The first access and mobility management function is identified in response to the request for information by retrieving the stored association.

6. The device according to any one of claims 2 to 5, wherein: The information indicating that the session is for the IMS service includes an indication that the session is for the IMS service.

7. The device according to any one of claims 2 to 5, wherein: The information indicating that the session is for an IMS service includes a data network name and / or a network slice identifier that can be used for the IMS service.

8. The device according to claim 1, wherein: The means for receiving information indicating that the registration corresponding to the first registration request is associated with an IMS service comprises means for receiving in the first registration request information indicating that the registration corresponding to the first registration request is associated with an IMS service.

9. The device according to claim 8, wherein: The information indicating that the session is for the IMS service includes an indication that the session is for the IMS service.

10. An apparatus according to any preceding claim, wherein: The network entity is configured to operate as a Home Subscriber System or an Application Server.

11. An apparatus according to any preceding claim, wherein: The means for obtaining include means for performing the following operations: signaling to the first access and mobility management function a request for information associated with the first registration identifier; as well as The requested information associated with the first registration identifier is received from the first access and mobility management function.

12. The device according to claim 11, wherein The information associated with the first registration identifier includes at least one of: a last activity time of the user equipment for the registration corresponding to the first registration request; a last active access type used by the user equipment for the registration corresponding to the first registration request; or an indication of whether IMS voice over packet switched sessions are supported in an area in which the user equipment is registered, for the registration corresponding to the first registration request.

13. An apparatus comprising: providing a first registration request for registering a user equipment to be served by the access and mobility management function to the unified data management function, wherein the first registration request includes a first registration identifier, wherein: The means are comprised in the access and mobility management function.

14. The device according to claim 13, wherein: The first registration request includes information indicating that the registration identifier is associated with an Internet Protocol Multimedia Subsystem (IMS) service.

15. The device according to claim 14, wherein: The apparatus comprises means for performing at least one of the following: receiving, from the user equipment, information indicating that the first registration request is associated with registration of the user equipment with a core network for an Internet Protocol Multimedia Subsystem (IMS) service; or Based on a packet data unit session established for the user equipment for a data network name and / or a network slice identifier corresponding to an Internet Protocol Multimedia Subsystem IMS service, it is determined that the first registration request is associated with the IMS service.

16. The device according to claim 15, wherein: The information indicating that the session is for an IMS service comprises an indication that the session is for an IMS service, wherein the indication is based on the information received from the user equipment.

17. The device according to any one of claims 13 to 16, wherein: The apparatus comprises components for performing the following operations: receiving a request from the unified data management function for information associated with the first registration identifier; as well as The requested information associated with the first registration identifier is signaled to the unified data management function.

18. The device according to claim 15, wherein: The information associated with the first registration identifier includes at least one of: a last activity time of the user equipment for the registration corresponding to the first registration request; a last active access type used by the user equipment for the registration corresponding to the first registration request; or an indication of whether IMS voice over packet switched sessions are supported in an area in which the user equipment is registered, for the registration corresponding to the first registration request.

19. The device according to any one of claims 12 to 16, wherein: The apparatus comprises means for providing the first registration identifier to a session management function in a packet data unit session establishment or modification request.

20. An apparatus comprising: providing a second registration request for registering that the session management function is to service a packet data unit session for the user equipment to the unified data management function, the second registration request comprising the first registration identifier, wherein: The second registration request comprises information indicating that the packet data unit session is associated with an Internet Protocol Multimedia Subsystem (IMS) service, wherein the apparatus is comprised in a session management function.

21. The device according to claim 18, wherein The apparatus comprises means for receiving, in a packet data unit session establishment or modification request, the first registration identifier from an access and mobility management function that is to serve the user equipment.

22. The device according to any one of claims 18 to 19, wherein: The information indicating that the session is for the IMS service includes an indication that the session is for the IMS service.

23. The device according to any one of claims 18 to 19, wherein: The information indicating that the session is for an IMS service includes a data network name and / or a network slice identifier that can be used for the IMS service.

24. An apparatus comprising: sending information to an access and mobility management function indicating that the first registration is associated with a registration of the user equipment with a core network for an Internet Protocol Multimedia Subsystem, IMS, service, wherein The apparatus is comprised in a user equipment.

25. A method comprising: receiving, from a first access and mobility management function, a first registration request for registering a user equipment to be served by the first access and mobility management function, the first registration request comprising a first registration identifier; receiving information indicating that the registration corresponding to the first registration request is associated with an Internet Protocol Multimedia Subsystem (IMS) service; receiving a request for information related to an IMS service from a network entity; Determine the registration identifiers and access and mobility management functions for the relevant IMS services; obtaining information for the associated IMS service from the determined access and mobility management function by providing the determined registration identifier to the determined access and mobility management function; as well as The requested information is provided to the network entity, wherein the method is performed by a device included in a unified data management function.

26. A method comprising: A first registration request for registering a user equipment to be served by an access and mobility management function is provided to a unified data management function, the first registration request comprising a first registration identifier, wherein the method is implemented by an apparatus included in the access and mobility management function.

27. A method comprising: A second registration request for registering that the session management function is to establish a packet data unit session for the user equipment is provided to the unified data management function, the second registration request comprising a first registration identifier, wherein the second registration request comprises information indicating that the packet data unit session is associated with an Internet Protocol Multimedia Subsystem IMS service, wherein the method is implemented by a device included in the session management function.

28. A method comprising: Information indicating that the first registration is associated with registration of the user equipment with a core network for Internet Protocol Multimedia Subsystem (IMS) services is sent to an access and mobility management function, wherein the method is implemented by an apparatus included in the user equipment.

29. A computer program comprising instructions which, when executed by an apparatus for unifying data management functions, cause the apparatus to: receiving, from a first access and mobility management function, a first registration request for registering a user equipment to be served by the first access and mobility management function, the first registration request comprising a first registration identifier; receiving information indicating that the registration corresponding to the first registration request is associated with an Internet Protocol Multimedia Subsystem (IMS) service; receiving a request from a network entity for information indicating which access and mobility management function is to provide IMS services to the user equipment; as well as An identifier of the first access and mobility management function is provided to the network entity using the received information and the received first registration request.

30. A computer program comprising instructions which, when executed by an apparatus for access and mobility functions, cause the apparatus to: A first registration request for registering a user equipment to be served by the access and mobility management function is provided to the unified data management function, the first registration request comprising a first registration identifier.

31. A computer program comprising instructions which, when executed by an apparatus for user session management functionality, cause the apparatus to: providing a second registration request for registering that the session management function is to service a packet data unit session for the user equipment to the unified data management function, the second registration request comprising the first registration identifier, wherein: The second registration request includes information indicating that the packet data unit session is associated with an Internet Protocol Multimedia Subsystem (IMS) service.

32. A computer program comprising instructions which, when executed by an apparatus for a user equipment, cause the apparatus to: Information indicating that the first registration is associated with registration of the user equipment with the core network for Internet Protocol Multimedia Subsystem, IMS, services is sent to the access and mobility management function.

Images