Abstract: A communication session for a UE can be restored in the event of serving call session control function (S-CSCF) node unavailability and/or application server (AS) unavailability by storing, prior to IMS unavailability, attribute-value pairs (AVPs) at a home subscriber server (HSS). These AVPs can be used independently by individual IMS nodes to restore a communication session for a UE due to an unavailable IMS node. When a first S-CSCF node becomes unavailable, a proxy CSCF (P-CSCF) node can send a SIP request originating from the UE to a second S-CSCF node. The second S-CSCF node can then send a request to the HSS for an identifier of an AS associated with the UE. Upon receipt of the AS identifier (e.g., an active AS name AVP) from the HSS, the second S-CSCF node can send the SIP request to the AS in order to restore the communication session for the UE.

Abstract: A network accessing method includes performing a cell search procedure for a first RAT; receiving first SI from a first cell of the first RAT when the first cell has been found in the cell search procedure; determining whether second SI is scheduled by the first cell according to content of the first SI; receiving the second SI in response to determination of the second SI being scheduled and deriving information regarding a second cell of a second RAT different from the first RAT; searching for the second cell according to the information regarding the second cell; and attempting to access the second cell instead of the first cell when the second cell has been found. The first cell is configured to provide access to a first core network and the second cell is configured to provide access to a second core network different from the first core network.

Abstract: A permissioned blockchain can be a decentralized data store that maintains information indicating whether user equipment (UE) is SIM locked and/or should be disabled. A UE can access the blockchain during boot up to determine if it should be disabled and not booted into a normal operating environment, and/or whether it is SIM locked to a particular carrier. Authorized entities, such as carriers and UE manufacturers, can update the blockchain to indicate that certain UEs should be disabled, are SIM locked, are not SIM locked, and/or whether it is permissible to remove SIM locks from those UEs.

Abstract: Method of dynamically assigning storage locations starts with the processor receiving a signal from a first client device associated with a first user. Processor stores a current location of the first client device in a historical database and determines whether a home location data associated with the first user matches the current location. In response to determining that the home location data associated with the first user does not match the current location, processor determines whether the first user has been associated with the current location at a greater frequency than the home location data based on the historical database. In response to determining that the first user has been associated with the current location at a greater frequency, processor updates the home location data associated with the first user to the current location. Other embodiments are described.

Abstract: A data storage change is received for a piece of data, wherein the data storage change is from a first location to a second location. Two or more possible paths to perform the data storage change are determined. A plurality of weights for each path of the two or more paths is determined. A weighted transfer time for each path of the two or more paths is determined.

Abstract: A method for combining two radio access network (RAN) cells into a virtual cell is disclosed, comprising: at a coordinating node, assigning a virtual cell identifier for a virtual cell, assigning a plurality of base stations to the virtual cell, and scheduling resources for a user equipment (UE) at each base station in the virtual cell; and at a base station of the plurality of base stations, constructing a signal containing two cell identifiers, the two cell identifiers being the virtual cell identifier and a physical cell identifier of the base station, and sending the signal to the UE, thereby improving performance for the UE at a cell edge of the first base station and of the second base station.

Abstract: A method of a network function (NF) entity performing communication in a wireless communication system includes: in case that a first registration request of a user equipment (UE) for a slice is received at an access and mobility function (AMF) entity through a first network, receiving a first slice availability request message for the slice from the AMF entity; determining whether the slice is available for the UE, based on a network slice policy; and transmitting, to the AMF entity, a response message including information regarding slice availability of the UE according to the first registration request, wherein in case that a second registration request of the UE for the slice is received at the AMF entity through a second network, slice availability of the UE according to the second registration request is determined based on at least one of the network slice policy or the information regarding the slice availability of the UE according to the first registration request.

Abstract: Provided are a method for a user equipment (UE) to perform access to a cell in a wireless communication, and an apparatus supporting the same. The method may include: receiving, from a first system, access control information for the first system; camping on the cell of a second system; mapping the access control information for the first system to access control information for the second system; and performing access to the cell of the second system, based on the mapped access control information for the second system.

Abstract: A user equipment (UE) may identify that an emergency call is being initiated and send further messages including the location of the UE. The UE receives emergency location signaling parameters, identifies that an emergency communication has been initiated by the UE based on the emergency location signaling parameters and transmits a message to an endpoint associated with emergency services based on the identification of the emergency message being initiated, wherein the message includes location information for the UE.

Abstract: A system that enables hanging lawful interception (LI) resources to be cleaned up includes a triggering function set comprising a plurality of triggering functions. The system also includes a data store comprising a plurality of auditing records corresponding to the plurality of triggering functions in the triggering function set. Each auditing record comprises a claimant attribute. Each triggering function sends an update request to the data store in response to being notified about a failed triggering function within the triggering function set. Each update request comprises a request to change ownership of the auditing record corresponding to the failed triggering function. A triggering function is selected as a new owner of the auditing record corresponding to the failed triggering function based at least in part on a match between the claimant attribute in the auditing record and a claimant field in the update request sent by the triggering function.

Abstract: The present invention relates to a method for operating a service application entity (100) configured to provide a service to a mobile entity (10) in a mobile communications network based on a client session, the method comprising: —determining a context information which comprises at least information required by another service application entity (400) providing the same type of service to continue the client session with the mobile entity, —pushing the context information towards a radio access node (300) of the mobile communications network to which the mobile entity is currently connected.

Abstract: A method for a communication between an application and a machine in a production or a physical object with the aid of a digital twin of a machine in a production or a physical object. Descriptive data including properties of digital data are generated based on a descriptive meta model. In addition, communication information is produced. To create the digital twin, the descriptive data, the communication information and a designation of the machine or the physical object are combined and stored in a list in order to create the digital twin. The application reads out the information of the list and uses it for a data exchange with the machine.

Abstract: The embodiments of the present disclosure provide a method and an apparatus for connection handling. The method includes: receiving a connection request that requests for establishing or resuming a connection with a base station; and instructing a Non-Access Stratum (NAS) of a terminal to perform a predetermined operation based on an obtained first connection result corresponding to the connection request. In this way, the problems associated with inconsistent operations in the user plane optimization in the related art can be solved and the consistency in operations between the Access Stratum (AS) and NAS of the terminal can be achieved.

Abstract: It is recognized herein that capabilities are lacking related to how different users can be authenticated on top of an existing subscription authentication. In some examples, a user¬ centric authentication layer may be supported on top of an existing subscription authentication, such that different users may use the same user equipment (UE) with customized services, and different users of devices can be identified behind a gateway with a 3GPP subscription (without the devices having a dedicated 3GPP subscription). Further, a user identifier may be linked to a subscription to access 3GPP services via non-3GPP access.

Abstract: The present disclosure relates to a communication method and system for converging a 5th-Generation (5G) communication system for supporting higher data rates beyond a 4th-Generation (4G) system with a technology for Internet of Things (IoT). The present disclosure may be applied to intelligent services based on the 5G communication technology and the IoT-related technology, such as smart home, smart building, smart city, smart car, connected car, health care, digital education, smart retail, security and safety services. There is disclosed a method, for a first network entity, for informing a change in coverage enhancement usage in a network comprising the first network entity and a user equipment (UE). The method comprises, in response to determining that a restriction on the use of coverage enhancement has changed for the UE, transmitting, to the UE, a first message including an indication of the change.

Abstract: An apparatus comprising means for performing: determining an expiration of a service request timer generated in association with a service request message from the apparatus; and handling the expiration of the service request timer based on a determination of a service type of the service request message.

Abstract: Location determination and telephone number distribution for emergency calls is enabled by a telephony system which maintains multiple pools of telephone numbers. Each pool corresponds to a different region such that the pools of telephone numbers are defined at the region-level rather than at the site-level. The telephony system determines the location of a calling device initiating an emergency call regardless of whether the calling device is at a known site. Based on the determined location of the calling device, one of the pools of telephone numbers which corresponds to that location is selected. The telephony system thereafter distributes a telephone number for the calling device to use for the emergency call from that selected pool of telephone numbers to facilitate an emergency call between the calling device and a local public safety answering point.

Abstract: Provided are a method and device for releasing radio resource control connection, a base station, a user equipment and a computer-readable storage medium. The method includes that a base station configures radio resource control connection release control information for a user equipment before the base station is triggered to release a radio resource control connection of the user equipment; and the base station makes a decision according to the radio resource control connection release control information when the base station releases the radio resource control connection of the user equipment.

Abstract: Techniques for optimizing terminating access domain selection (TADS) flow for a Fifth Generation (5G) standalone (SA) capable interworking device with legacy Fourth Generation (4G) voice over long term evolution (VoLTE) network are discussed herein. A 5G SA capable user equipment (UE) may receive a voice call from any generation network. To receive a 5G voice call on an IP Multimedia Subsystem (IMS) network, a terminating UE must be currently connected to a 5G SA network. However, the system has to determine the currently connected radio access technology (RAT) type before establishing a connection; otherwise, attempts to establish a 5G NR connection would result in network call completion errors. The system may configure a home subscriber server to receive a TADS request for the terminating UE and return a TADS status.

Abstract: The present disclosure relates to mobile edge computing (MEC) information obtaining methods and apparatus. One example method performed by a first network element includes receiving target reference information from a second network element, and sending, to the second network element, information about a MEC platform corresponding to the target reference information. The target reference information comprises target capability information.

Abstract: A method performed by a network node of a serving public land mobile network, PLMN, associated with a user equipment, UE, comprising: obtaining a secret identifier that uniquely identifies the UE, wherein the secret identifier is a secret that is shared between the UE and at least a home PLMN of the UE and that is shared by the home PLMN with the network node; and performing an operation related to the UE using the secret identifier. Other methods, computer programs, computer program products, network nodes and a serving PLMN are also disclosed.

Abstract: Various aspects include methods for supporting remote Subscriber Identity Module (SIM) profile provisioning that may be performed by a Lightweight Machine-to-Machine (LwM2M) server and LwM2M client computing devices, such as Internet of Things (IoT) devices. A LwM2M server may receive an indication of a SIM profile update for a LwM2M client computing device from a mobile network operator server, generating a remote SIM provisioning object for the LwM2M client computing device indicating that the SIM profile update for the LwM2M client computing device is available, and sending the remote SIM provisioning object to the LwM2M client computing device. A LwM2M computing device may receive a remote Subscriber Identity Module (SIM) provisioning object from a LwM2M server indicating that a SIM profile update for the LwM2M computing device is available, and download the SIM profile update in response to receiving the remote SIM provisioning object.

Abstract: A method is disclosed where a user equipment (“UE”) determines that the UE is in a connected mode. The UE then determines a connection type of the connected mode and prioritizes a measurement report based on the connection type. The method may also be performed by an integrated circuit of the UE.

Abstract: A method for configuring a wireless communication coverage extension system is described. The latter comprises a backhaul subnetwork in tree form comprising a plurality of interconnected nodes. At least two nodes directly connected to an internet access gateway are identified among the nodes of the backhaul subnetwork. A single node is selected from the at least two identified nodes to be the node through which a configuration of the wireless communication coverage extension system is defined. The configuration of the wireless communication coverage extension system defined is then sent from the selected node to all the other nodes of the backhaul subnetwork.

Abstract: A first request is received for a temporary alternate identifier for a user, wherein the user is identified within a service using a user service identifier, and wherein the temporary alternate identifier assists in transferring the user service identifier from the service to a resource. In response to the first request, the temporary alternate identifier is generated and associated with the user service identifier. The temporary alternate identifier is then provided the user, and the temporary alternate identifier is also provided by the user to the resource. A second request is received, from the resource, for an associated service identifier that is associated with the temporary alternate identifier. An indication is then provided, to the resource, that the user service identifier is the associated service identifier.

Abstract: There is described a system for restricting access to a mobile communications network for mobile communication devices within a restricted area. The system includes at least one transmitter operable to transmit a beacon signal for reception by mobile communication devices within the restricted area and an access control entity, communicable with the mobile communication device via a base station. The access control entity instructs a mobile communication device to perform at least one measurement of the beacon signal from each transmitter and then to provide measurement data corresponding to the performed measurement to the access control entity. The access control entity then analyses the measurement data provided by the mobile communication device and based on that analysis decides whether or not to provide the mobile communication device with access to a service of the mobile communications network.

Abstract: Methods, systems, and devices for communications are described. A device or a group of devices may generate data. The group of devices may receive a group profile from a node that identifies the devices to be included, and the group profile may include a function to be evaluated at each of the devices. The node may also provision evaluation parameters which may allow the device to provide authenticated aggregate data to a requesting third party, without sharing the data between the devices and without sharing the data with the node, thus concurrently maintaining individual data privacy and data provenance.

Abstract: Methods and systems are disclosed for managing registrations of computers. The methods and systems provide a registration tool that may be used to automatically register the computers. For each computer to be registered, information uniquely identifying the computer is collected and sent to a remote registration server. The information is then used by the remote registration server to perform the registration on behalf of the computer. The registration may be with a software vendor, a third-party database, or with the remote registration server itself in some cases. The registration server thereafter returns a registration code or other information to the computer to complete the registration. Such an arrangement allows the registration process to be controlled from a central location.

Abstract: An apparatus, and an associated method, for facilitating communication operations with a wireless device that is ICS or DTM capable. Signaling protocols and apparatus are provided for operation of the wireless device when an ICS with the wireless device is ongoing, and the device leaves an area that provides for ICS as well as when the ICS can be provided using circuit-switched connections.

Abstract: Disclosed herein are a method for tracking area update in a wireless communication system and an apparatus therefor. Specifically, a method for user equipment (UE) to perform a tracking area update (TAU) procedure in a wireless communication system comprises: a step of transmitting a TAU request message to a mobility management entity (MME); and a step of receiving a TAU accept message from the MME, wherein if the UE uses signaling optimization to enable the delivery of user data through a control plane over the MME, and the UE does not have pending user data to be transmitted through a user plane and has pending user data to be transmitted through the control plane over the MME, then a first active flag can be set in the TAU request message.

Abstract: Systems and methods for device registration and authentication are disclosed. In one embodiment, a method for authentication of a device may include (1) receiving, at a mobile device, a first credential; (2) transmitting, over a network, the first credential to a server; (3) receiving, from the server, a first key and a first value, the first value comprising a receipt for the first credential; (4) receiving, at the mobile device, a data entry for a second credential; (5) generating, by a processor, a second key from the data entry; (6) retrieving, by the mobile device, a third credential using the first key and the second key; (7) signing, by the mobile device, the first value with the third credential; and (8) transmitting, over the network, the signed third value to the server.

Abstract: Methods, systems, and devices for wireless communications are described. The described techniques provide for a user equipment (UE) to adjust a random access message that is transmitted to a base station in an asynchronous uplink transmission. The UE may use a constrained mapping of time and frequency resources for the random access message or transmit all portions of the message in a continuous transmission. The UE may also adjust the timing of the portions of the message. The base station may use a portion of the message, such as a preamble, to perform channel estimation for another portion of the message, such as a payload, to improve decoding of the transmitted message. Additionally, the UE may configure a waveform of the message to improve the continuous transmission of the message, for example by reducing interference between portions of the message.

Abstract: According to one configuration, while the user equipment is wirelessly connected to a first wireless base station over a first wireless communication link, a communication management resource in the user equipment receives input (such as a request) to tune-away the user equipment to a second wireless base station providing corresponding wireless services. To facilitate the temporary tune-away to the second wireless network, the communication management resource of the user equipment generates timing information associated with the switchover. In furtherance of the switchover (temporary tune-away) to the second wireless base station, the communication management resource of the user equipment transmits the timing information in a wireless communication over the first wireless communication link to the first wireless base station.

Abstract: The embodiments of the present disclosure relate to a cell selection method, a terminal device and a network device. The method includes obtaining, by a terminal device, an identifier of at least one cell corresponding to a network type supported by the terminal device; and determining, by the terminal device according to the identifier of the at least one cell, a target cell for cell selection or cell reselection. The network type is at least one of a Closed Access Group (CAG) network or a Stand-alone Non-Public Network (SNPN) network. The identifier of the at least one cell is an identifier of the CAG network or is an identifier of the SNPN network.

Abstract: Apparatuses, methods, and systems are disclosed for mobility management among multiple network slices. One apparatus includes a transceiver and a processor that establishes a first connection with a primary network slice and establishes a second connection with a secondary network slice of the same network while maintaining the first connection. In response to the processor detecting a mobility management (“MM”) event for the remote unit, the transceiver transmits a single MM request to the primary network slice via the first connection and receives a MM response via the first connection. In various embodiments, each network slice in the mobile communication network supports at least one of a plurality of service types, and wherein the MM response includes an update result for a service type provided by the primary network slice and a service type provided by the secondary network slice.

Abstract: A method performed by a first user equipment (UE) in a vehicle to everything (V2X) communication system, the method comprising: measuring, at least one parameter related to signal quality between the first UE and a cellular network; identifying a first event among a preconfigured set of events based on measuring of the at least one parameter; and transmitting, to a second UE, first information including information related to the first event and second information related to the first UE, based on a trigger of the first event, wherein the first information and the second information are for a prediction of the second UE associated with a state change of the cellular network, and wherein an operation of the second UE is based on the prediction.

Abstract: In an embodiment, there is provided a method for the support of data transmission in a packet mobile network, for PDN connectivity over the packet mobile network between an User Equipment UE and an external Packet Data Network PDN, the packet mobile network comprising a Core Network CN accessed by a Radio Access Network RAN, the data transmission using a tunnel over an interface between a serving RAN node and a serving user plane CN node, the method including support of the data transmission in a mode referred to as connectionless transmission mode, wherein the tunnel over the interface is predefined and identified using information referred to as Connection ID information, providing a reference to the PDN and to the serving user plane CN node.

Abstract: An object is to provide a network apparatus capable of performing a communication procedure suitable for accommodating an IoT device. A network apparatus (10) according to present disclosure includes a communication unit (11) configured to receive profile information of a communication terminal (20) transmitted from the communication terminal (20), and a determination unit (12) configured to determine, in a procedure for establishing a radio link between the network apparatus (10) and the communication terminal (20), whether or not to skip at least one of a procedure for configuring a radio resource used for communication of user data between the network apparatus (10) and the communication terminal (20) and a procedure for setting security between the network apparatus (10) and the communication terminal (20) according to the profile information, in which the communication unit (11) receives small data transmitted from the communication terminal (20) through the radio link.

Abstract: A method of establishing a Voice over Internet Protocol, VoI P, call between a calling User Equipment, UE, and a called UE, wherein said calling UE is served by a core network via a packet-switched radio access network, PS-RAN, and wherein a bearer is to be established between said calling U E and a gateway node in said core network, over said PS-RAN, for obtaining access to an Internet Protocol, IP, multimedia subsystem, I MS, network, wherein said method comprises the steps receiving, by a an IMS Call Session Control Function, CSCF, node a notification message thereby notifying said I MS node that said VoIP call establishment is in progress and initiating, by said I MS CSCF, re-establishment of said bearer between said calling UE and said gateway node, over said PS-RAN, in case said establishment of said bearer has failed due to a temporary failure.

Abstract: To send a message on a 5G or 6G network, a prospective user device must first perform a time-consuming and uncertain “blind search”, followed by a complex series of steps. Disclosed herein is a “network database”, a compendium of parameters about each base station, organized and searchable regionally, to simplify network access by providing the locations and connection information of base stations proximate to a prospective user before first contact. The database may be publicly accessible and downloadable for off-line use, and searchable by location to find the closest available base station. Compared with 5G/6G protocols, the network database may provide a simpler and quicker way to access local base stations. This is a great advantage in situations when even one-thousandth of a second can mean the difference between life and death, such as in roadway collision avoidance and harm minimization, and in situations involving V2X vehicle interconnectivity.

Abstract: Methods, systems, and apparatuses for protocol data unit (PDU) session management over different access technologies (ATs) are disclosed. A wireless transmit/receive unit (WTRU) may receive a first message from a network over a first access technology. The first message may include an indication for the WTRU to reestablish resources for one or more protocol data unit (PDU) sessions over a second access technology. The WTRU may determine that a PDU session of the one or more PDU sessions is locally deactivated by the WTRU. The WTRU may determine that it is in a limited service state associated with the second access technology. The WTRU may send a second message via the first access technology. The second message may include a PDU session status information element (IE) indicating the PDU session is locally deactivated such that the network releases the PDU session.

Abstract: Apparatuses, systems, and methods for a user equipment device (UE) to perform methods for network assisted side-link resource configuration for unicast and/or multi-cast/groupcast communications in V2X networks. A UE may, after establishing an RRC connection with a base station, transmit, to the base station, V2X connection information. The V2X connection information may include a V2X identifier associated with the UE and a V2X identifier associated with a target UE. The UE may receive, from the base station, a side-link configuration for data transmission with the target UE. The side-link configuration may include a resource allocation defined in time and frequency (e.g., a transmit/receive pool). The UE may communicate with the target UE using the resource allocation included in the side-link configuration.

Abstract: An infrastructure equipment comprising circuitry configured to transmit to a user equipment an RRC connection release message including assistance information for cell selection/reselection, the assistance information being based on location information.

Abstract: Selecting local gateways for VoWiFi and/or ViWiFi calls (voice traffic sessions) for a user equipment (UE) includes: receiving, by a routing node (evolved packet data gateway (ePDG)), a request to initiate the voice traffic session for the UE from a wireless node (WiFi router) communicatively coupled with the UE, the wireless node outside a cellular network; based on at least an internet protocol (IP) address of the wireless node or the UE, determining a geographical location of the UE; based on at least the geographical location of the UE, determining a tracking area code; based on at least the tracking area code, determining an IP address of a network gateway (user plane function (UPF) or packet data gateway (PGW) user plane function (PGW-U), and session management function (SMF) node or PGW control plane function (PGW-C)) proximate to the UE; and establishing the voice traffic session using the network gateway.

Abstract: Systems and techniques for distributed machine learning (DML) in an information centric network (ICN) are described herein. Finite message exchanges, such as those used in many DML exercises, may be efficiently implemented by treating certain data packets as interest packets to reduce overall network overhead when performing the finite message exchange. Further, network efficiency in DML may be improved achieved by using local coordinating nodes to manage devices participating in a distributed machine learning exercise. Additionally, modifying a round of DML training to accommodate available participant devices, such as by using a group quality of service metric to select the devices, or extending the round execution parameters to include additional devices, may have an impact on DML performance.

Abstract: A method and a device for hotspot leasing are provided. The method comprises: acquiring a data request packet transmitted by a requesting user (S11); based on a target data request packet acquired by a supplying user from the data request packet, transmitting hotspot information provided by the supplying user to the requesting user corresponding to the target data request packet, and establishing a hotspot leasing contract between the requesting user and the supplying user (S12). Therefore, demand docking is provided for both parties of leasing and selling by means of the data request packet, so that users with excess data provide data to users with data gaps. Urgent needs of one or more surrounding users are solved, near-field social contact for mutual assistance is established, and data utilization is improved.

Abstract: Embodiments include methods for a master node in a radio access network (RAN) to establish neighbor relations with a further RAN node, the master node operating in multi-connectivity towards a user equipment (UE) together with a secondary node in the RAN. Embodiments include determining that a first cell identifier associated with a cell is not included in a neighbor relations table maintained by the master node. Embodiments include sending, to the UE, a request to report a second cell identifier associated with the cell. The request includes the first cell identifier and is sent without determining whether the cell is a serving or neighbor cell for the UE. Embodiments include determining whether to establish a neighbor relation with a node associated with the first cell identifier, based on a report from the UE in response to the request. Embodiments also include complementary methods performed by a UE.

Abstract: A method for steering a mobile device to a preferred network, such as a Private LTE network or a 5G network, in a scenario in which the coverage area of the preferred network overlaps the coverage area of a non-preferred network. A preferred network list is provisioned into a SIM/eSIM module at the mobile device side. The steering application is hosted at the home network and periodically triggers the home network to request from the visited network a set of values for attributes associated with a current location of the mobile device. Based on these values, the steering application determines whether the mobile device is within the coverage area of the preferred network and, if so, directs the home network to send a cancel location request to the non-preferred visited network, thereby triggering the mobile device to attach to the preferred network.

Abstract: In order to secure interceptible calls end-to-end, an intermediate MIKEY server is used to allow an intermediate SIP server to communicate with a key-management server. The intermediate SIP server intercepts call elements when a call is initialized among a plurality of terminal devices. The intermediate SIP server supplies these intercepted elements to the intermediate MIKEY server, which then establishes a dialogue with the key-management server on the basis of these elements. The result of this dialogue is sent back to the intermediate SIP server, which records same as call metadata allowing direct or deferred use of the call content.

Abstract: A method for implementing an IP Multimedia Subsystem (IMS) registration, includes: a Home Subscriber Server (HSS) recording a current registration state of a User Equipment (UE) in response to receiving a Multimedia Authentication Request (MAR) initiated by a Service Call Session Control Function (S-CSCF) selected for the UE when a first Register request is sent by the UE; in response to receiving a second Register request initiated by an Interrogating Call Session Control Function (I-CSCF), the HSS sends the S-CSCF Name to the I-CSCF when the current registration state of the UE is an assigned S-CSCF state. By the scheme, a same S-CSCF is ensured to be used in the two User Authentication Request/User Authentication Answer (UAR/UAA) procedures of the initial IMS registration procedure, and the initial IMS registration of the UE is implemented successfully.