IMS registration method, system and device, network element equipment and storage medium

Abstract

The invention relates to an IMS registration method, system and device, network element equipment and a storage medium. The method is applied to a P-CSCF, and comprises the following steps: inserting an address of the S-CSCF into a re-registration message; and forwarding the re-registration message to the I-CSCF, so that the I-CSCF identifies the address of the S-CSCF in the re-registration message, and forwarding the re-registration message to the address of the S-CSCF under the condition that the address of the S-CSCF exists. By adopting the method, the resource consumption of the DRA signaling network and the HSS or the UDM can be reduced.

Description

Technical Field

[0001] The present application relates to the field of communication technology, and in particular to an IMS registration method, system, apparatus, computer equipment, and storage medium. Background Art

[0002] In recent years, IMS (IP Multimedia Subsystem) networks have become the mainstream voice network. The all-IP links used by IMS networks can meet users' diverse audio and video needs.

[0003] When a user equipment (UE) is turned on or when mobile data is enabled after turning off airplane mode, it initiates an initial registration request with the IMS network. During the initial registration process, the Home Subscriber Server (HSS) in 4G networks or the Unified Data Management (UDM) in 5G networks stores the addresses of the user's subscribed P-CSCF (Proxy-Call Session Control Function) and Serving-Call Session Control Function (S-CSCF). The P-CSCF and S-CSCF also store each other's addresses. After successful initial registration, the UE periodically performs refresh registrations (also known as re-registration or periodic registration) to confirm that the connection with the IMS network is functioning properly. During the refresh registration process, the Interrogating-Call Session Control Function (I-CSCF) in the IMS network queries the HSS through the Diameter Routing Agent (DRA) signaling network to obtain the address of the user's subscribed S-CSCF. According to the registration statistics of the existing network, refresh registration messages account for 90%. Each refresh registration requires querying the HSS or UDM through the DRA signaling network, which consumes a large amount of DRA signaling network and HSS or UDM resources, resulting in a waste of DRA signaling network and HSS or UDM resources. Summary of the Invention

[0004] Based on this, it is necessary to provide an IMS registration method, system, apparatus, network element device and storage medium to address the above technical issues.

[0005] In a first aspect, the present application provides an IMS registration method, applied to a P-CSCF, the method comprising:

[0006] Insert the S-CSCF address into the re-registration message;

[0007] The re-registration message is forwarded to the I-CSCF, so that the I-CSCF identifies the address of the S-CSCF in the re-registration message and forwards the re-registration message to the address of the S-CSCF if the address of the S-CSCF exists.

[0008] In one embodiment, inserting the address of the S-CSCF into the re-registration message includes:

[0009] Insert the S-CSCF address into the new header field of the re-registration message.

[0010] In one embodiment, inserting the address of the S-CSCF into a new header field of the re-registration message includes:

[0011] In case of HSS and / or UDM failure, the address of the S-CSCF is inserted into a new header field of the re-registration message.

[0012] In one embodiment, inserting the address of the S-CSCF into a new header field of the re-registration message includes:

[0013] Check the registration status of the UE;

[0014] In the case that the UE has been registered, the address of the S-CSCF is inserted into the new header field of the re-registration message.

[0015] In one embodiment, detecting the registration status of the UE includes:

[0016] Determine a value of integrity protection, and determine that the UE is registered when the value of integrity protection is a first value, or determine that the UE is not registered when the value of integrity protection is a second value.

[0017] In a second aspect, the present application provides an IMS registration method, applied to an I-CSCF, the method comprising:

[0018] receiving a re-registration message forwarded by the P-CSCF to the I-CSCF;

[0019] identifying an address of an S-CSCF in the re-registration message, the address of the S-CSCF being inserted into the re-registration message by the P-CSCF;

[0020] If the address of the S-CSCF exists, forward the re-registration message to the address of the S-CSCF.

[0021] In one embodiment, identifying the address of the S-CSCF in the re-registration message includes:

[0022] Identify new header fields in re-registration messages;

[0023] In a case where the new header field exists, the address of the S-CSCF is obtained from the new header field.

[0024] In one embodiment, the method further comprises:

[0025] If the address of the S-CSCF does not exist, send a UAR message to the HSS;

[0026] receiving a UAA message sent by the HSS in response to the UAR message, and obtaining an address of the S-CSCF from the UAA message;

[0027] The re-registration message is forwarded to the address of the S-CSCF.

[0028] In one embodiment, the sending of the UAR message to the HSS includes:

[0029] When the HSS is normal, a UAR message is sent to the HSS.

[0030] In a third aspect, the present application provides an IMS registration system, which includes a P-CSCF, an I-CSCF, and an S-CSCF, wherein:

[0031] the P-CSCF, configured to insert the address of the S-CSCF into a re-registration message, and forward the re-registration message to the I-CSCF;

[0032] The I-CSCF is configured to identify the address of the S-CSCF in the re-registration message, and forward the re-registration message to the address of the S-CSCF if the address of the S-CSCF exists.

[0033] In one of the embodiments, the S-CSCF is configured to interact with the HSS, and when the HSS does not respond or the HSS returns an error code, skip the interaction with the HSS and return a 200 OK message to the UE.

[0034] In one of the embodiments, the S-CSCF is further used to generate disaster recovery information based on the re-registration message, and to send a SAR message to the HSS if the disaster recovery information does not match the disaster recovery information stored in the S-CSCF; or to return the 200 OK message to the UE if the disaster recovery information matches the disaster recovery information stored in the S-CSCF.

[0035] In a fourth aspect, the present application further provides an IMS registration device. The device includes:

[0036] An insertion module, configured to insert the address of the S-CSCF into the re-registration message;

[0037] The sending module is used to forward the re-registration message to the I-CSCF, so that the I-CSCF identifies the address of the S-CSCF in the re-registration message and forwards the re-registration message to the address of the S-CSCF if the address of the S-CSCF exists.

[0038] In one embodiment, the insertion module is further used to:

[0039] Insert the S-CSCF address into the new header field of the re-registration message.

[0040] In one embodiment, the insertion module is further used to:

[0041] In case of HSS and / or UDM failure, the address of the S-CSCF is inserted into a new header field of the re-registration message.

[0042] In one embodiment, the insertion module is further used to:

[0043] Check the registration status of the UE;

[0044] In the case that the UE has been registered, the address of the S-CSCF is inserted into the new header field of the re-registration message.

[0045] In one embodiment, the insertion module is further used to:

[0046] Determine a value of integrity protection, and determine that the UE is registered when the value of integrity protection is a first value, or determine that the UE is not registered when the value of integrity protection is a second value.

[0047] In a fifth aspect, the present application further provides an IMS registration device. The device includes:

[0048] A first receiving module is configured to receive a re-registration message forwarded by the P-CSCF to the I-CSCF;

[0049] an identification module, configured to identify an address of an S-CSCF in the re-registration message, wherein the address of the S-CSCF is inserted into the re-registration message by the P-CSCF;

[0050] The first forwarding module is configured to forward the re-registration message to the address of the S-CSCF if the address of the S-CSCF exists.

[0051] In one embodiment, the identification module is further configured to:

[0052] Identify new header fields in re-registration messages;

[0053] In a case where the new header field exists, the address of the S-CSCF is obtained from the new header field.

[0054] In one embodiment, the apparatus further comprises:

[0055] a sending module, configured to send a UAR message to the HSS if the address of the S-CSCF does not exist;

[0056] a second receiving module, configured to receive a UAA message sent by the HSS in response to the UAR message, and obtain the address of the S-CSCF from the UAA message;

[0057] The second forwarding module is configured to forward the re-registration message to the address of the S-CSCF.

[0058] In one embodiment, the first forwarding module is further configured to:

[0059] When the HSS is normal, a UAR message is sent to the HSS.

[0060] In a sixth aspect, the present application further provides a network element device, including a processor and a transmitter;

[0061] The processor is configured to insert the address of the S-CSCF into the re-registration message;

[0062] The transmitter is configured to forward the re-registration message to the I-CSCF, so that the I-CSCF identifies the address of the S-CSCF in the re-registration message, and forwards the re-registration message to the address of the S-CSCF if the address of the S-CSCF exists.

[0063] In a seventh aspect, the present application further provides a network element device, including a receiver, a processor, and a transmitter;

[0064] The receiver is configured to receive a re-registration message forwarded by the P-CSCF to the I-CSCF;

[0065] the processor being configured to identify an address of an S-CSCF in the re-registration message, the address of the S-CSCF being inserted into the re-registration message by the P-CSCF;

[0066] The transmitter is configured to forward the re-registration message to the address of the S-CSCF if the address of the S-CSCF exists.

[0067] In an eighth aspect, the present application further provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program implements any of the above methods when executed by a processor.

[0068] In a ninth aspect, the present application further provides a computer program product, comprising a computer program, which implements any of the above methods when executed by a processor.

[0069] The above-mentioned IMS registration method, system, apparatus, network element equipment and storage medium enable the P-CSCF to insert the address of the S-CSCF into the re-registration message and then forward the re-registration message to the I-CSCF. The I-CSCF determines whether the re-registration message carries the address of the S-CSCF. If the re-registration message includes the address of the S-CSCF, the I-CSCF obtains the address of the S-CSCF and forwards the re-registration message to the S-CSCF, so that the S-CSCF completes the subsequent re-registration process for the UE. The embodiment of the present application enables the P-CSCF to insert the address of the S-CSCF into the re-registration message, so that the I-CSCF can obtain the address of the HSS or UDM without interacting with the HSS or UDM through the DRA signaling network during the re-registration process, thereby reducing the resource consumption of the DRA signaling network and the HSS or UDM. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] Figure 1 FIG1 is a flow chart of an IMS registration method according to an embodiment;

[0071] Figure 2 FIG1 is a flow chart of an IMS registration method according to an embodiment;

[0072] Figure 3 FIG1 is a flow chart of an IMS registration method according to an embodiment;

[0073] Figure 4 304 is a flowchart of an embodiment;

[0074] Figure 5FIG1 is a flow chart of an IMS registration method according to an embodiment;

[0075] Figure 6 is a schematic diagram of an IMS registration system in one embodiment;

[0076] Figure 7 FIG. 1 is a flow chart of interaction between an S-CSCF and an HSS in one embodiment;

[0077] Figure 8 is a structural block diagram of an IMS registration device in one embodiment;

[0078] Figure 9 is a structural block diagram of an IMS registration device in one embodiment;

[0079] Figure 10 Schematic diagram of the structure of a network element device in one embodiment;

[0080] Figure 11 FIG. 1 is a structural diagram of a network element device in an embodiment. DETAILED DESCRIPTION

[0081] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0082] In one embodiment, Figure 1 As shown, an IMS registration method is provided. This embodiment of the application is described by applying this method to a P-CSCF in an IMS system, including the following steps:

[0083] Step 102: Insert the address of the S-CSCF into the re-registration message.

[0084] In the embodiment of the present application, the user equipment sends a re-registration message to the P-CSCF before its registration in the IMS network expires. Since the user equipment will preferentially send the re-registration message to the P-CSCF with which the user equipment initially subscribed when re-registering, and the P-CSCF with which the user equipment initially subscribed stores the address of the S-CSCF with which the user equipment subscribed during the initial registration process of the user equipment, the P-CSCF can obtain the address of the S-CSCF with which the user equipment subscribed from itself after receiving the re-registration message.

[0085] The P-CSCF inserts the address of the S-CSCF to which the user equipment is subscribed into the re-registration message. The embodiment of the present application does not specifically limit the location where the S-CSCF address is inserted. For example, the structure of the re-registration message may not be changed, and the address of the S-CSCF may be inserted into the valid data portion carried by the re-registration message, so that the I-CSCF obtains the address of the S-CSCF by parsing the valid data portion of the re-registration message. Alternatively, a new data structure may be added to the re-registration message, for example, a new header field may be added to the re-registration message, and the address of the S-CSCF may be inserted into the new header field, so that the I-CSCF obtains the address of the S-CSCF from the new header field.

[0086] Step 104: forward the re-registration message to the I-CSCF, so that the I-CSCF identifies the address of the S-CSCF in the re-registration message, and forwards the re-registration message to the address of the S-CSCF if the address of the S-CSCF exists.

[0087] In this embodiment of the present application, after inserting the S-CSCF address into the re-registration message, the P-CSCF forwards the re-registration message to the I-CSCF. Upon receiving the re-registration message, the I-CSCF obtains the S-CSCF address from the message and forwards the re-registration message to the S-CSCF address, specifically the S-CSCF to which the user device is subscribed. The S-CSCF then interacts with the HSS to complete the user device's re-registration process.

[0088] The IMS registration method provided in the embodiment of the present application enables the P-CSCF to insert the address of the S-CSCF into the re-registration message and then forward the re-registration message to the I-CSCF. The I-CSCF determines whether the re-registration message carries the address of the S-CSCF. If the re-registration message includes the address of the S-CSCF, the I-CSCF obtains the address of the S-CSCF and forwards the re-registration message to the S-CSCF, so that the S-CSCF completes the subsequent re-registration process for the UE. By enabling the P-CSCF to insert the address of the S-CSCF into the re-registration message, the embodiment of the present application enables the I-CSCF to obtain the address of the HSS or UDM without interacting with the HSS or UDM through the DRA signaling network during the re-registration process, thereby reducing the resource consumption of the DRA signaling network and the HSS or UDM.

[0089] In one embodiment, in step 102, inserting the S-CSCF address into the re-registration message includes inserting the S-CSCF address into a new header field of the re-registration message. In this embodiment of the present application, a new header field (a new header field) is added to the re-registration message, and the P-CSCF inserts the S-CSCF address into the new header field, allowing the I-CSCF to obtain the S-CSCF address by reading the content of the new header field. This approach eliminates the need to add the I-CSCF the ability to parse re-registration messages, minimizes functional changes to the current I-CSCF, and reduces the cost of upgrading the I-CSCF.

[0090] In one embodiment, inserting the address of the S-CSCF into a new header field of the re-registration message includes:

[0091] In case of HSS and / or UDM failure, the address of the S-CSCF is inserted into a new header field of the re-registration message.

[0092] In an embodiment of the present application, the P-CSCF may insert the address of the S-CSCF into the new header field of the re-registration message when the HSS or UDM fails, so that the I-CSCF obtains the address of the S-CSCF by reading the content of the new header field. When the HSS or UDM is normal, the address of the S-CSCF is not inserted into the new header field of the re-registration message, so that the I-CSCF obtains the address of the S-CSCF through the existing method.

[0093] The following description will be made using HSS as an example. The P-CSCF can maintain an HSS status identifier, which is used to characterize the status of the HSS. The HSS status identifier can include a first identifier and a second identifier, wherein the first identifier is used to characterize that the HSS is normal and the second identifier is used to characterize that the HSS is faulty. For example, the first identifier can be 0 and the second identifier can be 1, or the first identifier can be set to 1 and the second identifier to 0. This embodiment of the present application does not specifically limit this.

[0094] The P-CSCF can determine the status of the HSS by regularly interacting with the HSS, and then set the HSS status identifier accordingly according to the status of the HSS. Alternatively, the status of the HSS can be determined by other network elements of the IMS network, and a message can be sent to the P-CSCF after determining the status of the HSS. The P-CSCF determines the status of the HSS based on the received message and sets the HSS status identifier accordingly. This embodiment of the present application does not specifically limit this. The process for the P-CSCF to determine whether the UDM is normal in the 5G network can be found in the above process, and the embodiment of the present application will not be repeated here.

[0095] The IMS registration method provided in the embodiments of the present application enables the P-CSCF to insert the S-CSCF address into the re-registration message in the event of an HSS or UDM failure, allowing the I-CSCF to obtain the S-CSCF address from the re-registration message. When the HSS or UDM is in a normal state, the I-CSCF obtains the S-CSCF address through existing methods. Therefore, the method provided in the embodiments of the present application can be used as a backup solution, performing IMS registration through existing procedures when the HSS or UDM is normal, and ensuring that the re-registration message can reach the S-CSCF in the event of an HSS or UDM failure.

[0096] In one embodiment, Figure 2 As shown, the address of the S-CSCF is inserted into the new header field of the re-registration message, including:

[0097] Step 202: Detect the registration status of the UE.

[0098] Step 204: If the UE has been registered, insert the address of the S-CSCF into the new header field of the re-registration message.

[0099] In this embodiment of the present application, after receiving the re-registration message, the P-CSCF detects the registration status of the user device that sent the re-registration message. The registration status is divided into unregistered and registered. Unregistered indicates that the user device has not previously performed initial registration with the IMS network, and registered indicates that the user device has previously performed initial registration with the IMS network.

[0100] Since the P-CSCF only stores the address of the user device's S-CSCF if the user device has initially registered with it (that is, if it is the P-CSCF with which the user device initially subscribed), the P-CSCF can only obtain the address of the user device's S-CSCF and insert the S-CSCF address into the new header field of the re-registration message if the user device has already registered. If the P-CSCF determines that the user device has not initially registered, there are two possible scenarios: the P-CSCF is not the P-CSCF with which the user device initially subscribed, or the user device has indeed not initially registered. (In this case, the registration message sent by the user device is not a re-registration message, but an initial registration message.) In either case, the P-CSCF forwards the re-registration message to the I-CSCF without inserting any content into the new header field of the re-registration message, completing the user device's re-registration (or initial registration) process through existing procedures.

[0101] In one embodiment, in step 202, detecting the registration status of the UE includes:

[0102] Determine a value of integrity protection, and determine that the UE is registered when the value of integrity protection is a first value, or determine that the UE is not registered when the value of integrity protection is a second value.

[0103] In this embodiment of the present application, the P-CSCF performs integrity verification on the re-registration message to determine whether the user equipment has already been registered. If the integrity-protected value obtained by the P-CSCF after the integrity verification is a second value (the second value can be no, 0, 1, etc., and the specific selection can be made by those skilled in the art), the P-CSCF determines that the user equipment is an initial registration (unregistered) and adds a tag with the second value of integrity-protected, such as integrity-protected=no, to the Authorization header field of the registration message. If the integrity-protected value obtained by the P-CSCF after the integrity verification is a first value (the first value can be yes, 1, 0, etc., and the specific selection can be made by those skilled in the art), the P-CSCF determines that the user equipment is re-registering (already registered) and adds a tag with the first value of integrity-protected, such as integrity-protected=yes, to the Authorization header field of the re-registration message.

[0104] The IMS registration method provided in the embodiment of the present application detects the registration status of the UE and, if the UE is already registered, enables the P-CSCF to insert the address of the S-CSCF into the re-registration message. This allows the I-CSCF to obtain the address of the HSS or UDM without having to interact with the HSS or UDM through the DRA signaling network during the re-registration process, thereby reducing resource consumption of the DRA signaling network and the HSS or UDM.

[0105] In one embodiment, Figure 3 As shown, an IMS registration method is provided. This embodiment of the application is described by applying the method to the I-CSCF in the IMS system, including the following steps:

[0106] Step 302: Receive a re-registration message forwarded by the P-CSCF to the I-CSCF.

[0107] In the embodiment of the present application, after the user equipment sends a re-registration message to the P-CSCF, the P-CSCF forwards the re-registration message to the I-CSCF. The I-CSCF receives the re-registration message forwarded by the P-CSCF.

[0108] Step 304: Identify the address of the S-CSCF in the re-registration message. The address of the S-CSCF is inserted into the re-registration message by the P-CSCF.

[0109] In this embodiment of the present application, the I-CSCF identifies the S-CSCF address inserted into the re-registration message by the P-CSCF from the re-registration message. If the data structure of the re-registration message is not modified, that is, the S-CSCF address is inserted into the payload portion of the re-registration message, the I-CSCF obtains the S-CSCF address by parsing the payload portion of the re-registration message. If a new data structure, such as a new header field, is added to the re-registration message, the I-CSCF obtains the S-CSCF address from the new data structure.

[0110] Step 306: If the address of the S-CSCF exists, forward the re-registration message to the address of the S-CSCF.

[0111] In the embodiment of the present application, if the I-CSCF obtains the address of the S-CSCF from the re-registration message, it forwards the re-registration message to the address of the S-CSCF. If the I-CSCF fails to obtain the address of the S-CSCF from the re-registration message, the I-CSCF may interact with the HSS or UDM through existing procedures to obtain the address of the S-CSCF, and then forward the re-registration message to the address of the S-CSCF.

[0112] The IMS registration method provided in the embodiment of the present application enables the P-CSCF to insert the address of the S-CSCF into the re-registration message and then forward the re-registration message to the I-CSCF. The I-CSCF determines whether the re-registration message carries the address of the S-CSCF. If the re-registration message includes the address of the S-CSCF, the I-CSCF obtains the address of the S-CSCF and forwards the re-registration message to the S-CSCF, so that the S-CSCF completes the subsequent re-registration process for the UE. By enabling the P-CSCF to insert the address of the S-CSCF into the re-registration message, the embodiment of the present application enables the I-CSCF to obtain the address of the HSS or UDM without interacting with the HSS or UDM through the DRA signaling network during the re-registration process, thereby reducing the resource consumption of the DRA signaling network and the HSS or UDM.

[0113] In one embodiment, Figure 4 As shown, in step 304, identifying the address of the S-CSCF in the re-registration message includes:

[0114] Step 402: Identify the new header field in the re-registration message;

[0115] Step 404: If the new header field exists, obtain the address of the S-CSCF from the new header field.

[0116] In this embodiment of the present application, a new header (a new header) is added to the re-registration message, and the P-CSCF inserts the S-CSCF address into the new header. The I-CSCF can identify whether the new header in the re-registration message exists, that is, whether the new header carries valid data. If the new header carries valid data, the new header is considered to exist; if not, the new header is considered to not exist.

[0117] If the new header field exists, the I-CSCF obtains the address of the S-CSCF carried in the new header field. If the new header field does not exist, the I-CSCF interacts with the HSS or UDM through the existing process to obtain the address of the S-CSCF. The I-CSCF forwards the re-registration message to the address of the S-CSCF, that is, to the S-CSCF subscribed to the user device. The S-CSCF subsequently interacts with the HSS or UDM to complete the re-registration process of the user device.

[0118] The IMS registration method provided in the embodiments of the present application adds a new header field to the re-registration message, and inserts the address of the S-CSCF into the new header field. The I-CSCF detects the presence of the new header field (that is, whether the new header field contains valid data) and, if so, obtains the address of the S-CSCF from the new header field. This method eliminates the need to add the ability to parse re-registration messages to the I-CSCF, requiring minimal changes to the existing I-CSCF functionality, thereby reducing the cost of upgrading the I-CSCF.

[0119] In one embodiment, Figure 5 As shown, the above method also includes:

[0120] Step 502: If the address of the S-CSCF does not exist, a UAR message is sent to the HSS.

[0121] Step 504: Receive a UAA message sent by the HSS in response to the UAR message, and obtain the address of the S-CSCF from the UAA message;

[0122] Step 506: forward the re-registration message to the address of the S-CSCF.

[0123] In an embodiment of the present application, if the S-CSCF address does not exist, the I-CSCF obtains the S-CSCF address through existing procedures. The I-CSCF sends a UAR (User Authorization Request) message to the HSS to query the S-CSCF address subscribed to the user equipment. The HSS responds to the UAR message and returns a UAA (User Authorization Answer) message. The UAA message carries the S-CSCF address subscribed to the user equipment. The I-CSCF can then obtain the S-CSCF address from the UAA message and forward the re-registration message to the S-CSCF address.

[0124] In one embodiment, in step 502, sending a UAR message to the HSS includes:

[0125] If the HSS is normal, a UAR message is sent to the HSS.

[0126] In the embodiment of the present application, the I-CSCF may send a UAR message to the HSS when the HSS is normal, and will not interact with the HSS when the HSS fails. The I-CSCF may also maintain an HSS status identifier, which is used to characterize the status of the HSS. For the specific definition of the HSS status identifier, please refer to the description of the aforementioned embodiment, and the embodiment of the present application will not be repeated here. When the HSS status identifier indicates that the HSS status is normal, the I-CSCF may obtain the address of the S-CSCF by sending a UAR message to the HSS.

[0127] Generally speaking, in the event of an HSS failure, the P-CSCF will insert the S-CSCF address into the re-registration message, and the I-CSCF can obtain the S-CSCF address from the re-registration message, which does not involve any interaction with the HSS. However, considering that the P-CSCF to which the user equipment sends the re-registration message may not be the P-CSCF with which the user equipment initially signed a contract, or the user equipment has not performed initial registration, in this case the re-registration message will not carry the S-CSCF address, which means that in the event of an HSS failure, the re-registration message may not carry the S-CSCF address. In this case, the I-CSCF can temporarily store the UAR message and wait until it determines that the HSS status is normal before sending a UAR message to the HSS to obtain the S-CSCF address.

[0128] The I-CSCF can determine whether the HSS is normal based on its interaction with the HSS and modify the HSS status flag accordingly. Alternatively, other network elements in the IMS network can determine whether the HSS is normal and send a message to the I-CSCF to inform it of the normal status of the HSS.

[0129] In the 5G network, the way in which the I-CSCF interacts with the UDM through the existing process to obtain the S-CSCF address can refer to the existing technology, and the embodiments of this application will not be repeated here.

[0130] The IMS registration method provided in the embodiment of the present application can be applied to the scenario where the method provided in the embodiment of the present application is used as a backup solution, and IMS registration is performed through the existing process when the HSS is normal, so that the re-registration message can also reach the S-CSCF in the event of an HSS failure.

[0131] In one embodiment, an IMS registration system is provided. Figure 6 As shown, the system includes a P-CSCF, an I-CSCF and an S-CSCF, wherein the P-CSCF is used to insert the address of the S-CSCF into the re-registration message and forward the re-registration message to the I-CSCF; the I-CSCF is used to identify the address of the S-CSCF in the re-registration message and forward the re-registration message to the address of the S-CSCF if the address of the S-CSCF exists.

[0132] In an embodiment of the present application, before the user device's registration in the IMS network expires, the user device sends a re-registration message to the P-CSCF. After receiving the re-registration message, the P-CSCF obtains the address of the S-CSCF to which the user device subscribes. If the P-CSCF is the P-CSCF with which the user device initially subscribes, since the P-CSCF and the S-CSCF have stored each other's addresses during the user device's initial registration, the P-CSCF can obtain the address of the S-CSCF to which the user device subscribes from within its own message. If the P-CSCF is not the P-CSCF with which the user device initially subscribes, the P-CSCF can interact with the HSS or UDM to obtain the address of the S-CSCF, or it can send a re-registration message without the S-CSCF address to the I-CSCF, allowing the I-CSCF to obtain the address of the S-CSCF according to the existing re-registration process. The S-CSCF address can be inserted into the payload portion of the re-registration message, or a new header field can be added to the re-registration message, into which the S-CSCF address is inserted.

[0133] The P-CSCF continues to forward the re-registration message to the I-CSCF. After receiving the re-registration message, the I-CSCF identifies whether the re-registration message carries the address of the S-CSCF. If the address of the S-CSCF is not carried, the I-CSCF follows the existing re-registration process and interacts with the HSS or UDM through the DRA signaling network to obtain the address of the S-CSCF to which the user equipment is subscribed. If the address of the S-CSCF exists, the I-CSCF forwards the re-registration message to the address of the S-CSCF, that is, to the S-CSCF to which the user equipment is subscribed. The S-CSCF subsequently interacts with the HSS or UDM to complete the re-registration process of the user equipment.

[0134] The IMS registration system provided in the embodiment of the present application enables the P-CSCF to insert the address of the S-CSCF into the re-registration message and then forward the re-registration message to the I-CSCF. The I-CSCF determines whether the re-registration message carries the address of the S-CSCF. If the re-registration message includes the address of the S-CSCF, the I-CSCF obtains the address of the S-CSCF and forwards the re-registration message to the S-CSCF, so that the S-CSCF completes the subsequent re-registration process for the UE. By enabling the P-CSCF to insert the address of the S-CSCF into the re-registration message, the embodiment of the present application enables the I-CSCF to obtain the address of the HSS or UDM without interacting with the HSS or UDM through the DRA signaling network during the re-registration process, thereby reducing the resource consumption of the DRA signaling network and the HSS or UDM.

[0135] In one embodiment, Figure 7 As shown, the S-CSCF is also used to interact with the HSS, and in the case where the HSS has no response or the HSS returns an error code, the S-CSCF skips the interaction with the HSS and returns a 200 OK message to the UE.

[0136] In an embodiment of the present application, the S-CSCF may have the need to conduct one or more rounds of interaction with the HSS during the re-registration process, for example, the S-CSCF verifies with the HSS whether the contract information of the user device is consistent with the last time the user device re-registered, updates the contract information of the user device stored in the HSS, etc. When the S-CSCF interacts with the HSS, the HSS may fail or be overloaded, which is specifically manifested in that after the S-CSCF sends a message, it fails to respond to the S-CSCF's message for a certain period of time (that is, no response), or sends an error code to the S-CSCF. If the S-CSCF continues to try to complete the interaction with the HSS, it may happen that the HSS has no response or returns an error code, resulting in the user device being unable to complete the re-registration process.

[0137] Therefore, if the HSS does not respond or the HSS returns an error code, the S-CSCF can skip subsequent interactions with the HSS and directly return a 200 OK message (information indicating a successful request) to the user equipment, so that the user equipment can end the re-registration process. The S-CSCF can skip subsequent interactions with the HSS if the HSS does not respond to a message or returns an error code. Alternatively, a preset condition can be set so that the S-CSCF skips subsequent interactions with the HSS if the interaction process between the S-CSCF and the HSS meets the preset condition. The specific content of the preset condition can be set by technical personnel according to actual needs. For example, the preset condition can be set so that the HSS still does not respond after the S-CSCF repeatedly sends the same information to the HSS a preset number of times; or it can be set so that the number of times the HSS does not respond or returns an error code reaches a preset number during the entire interaction process between the S-CSCF and the HSS. This embodiment of the present application does not specifically limit this.

[0138] After skipping the interaction with the HSS, the S-CSCF returns a 200 OK message to the user equipment. The S-CSCF can send a 200 OK message to the I-CSCF, so that the I-CSCF sends a 200 OK message to the P-CSCF after receiving the 200 OK message, and the P-CSCF then sends a 200 OK message to the user equipment. The S-CSCF can also continue to complete the previously unfinished re-registration process with the HSS after the HSS fault is recovered. For example, the HSS can send a message to the S-CSCF after the fault is recovered, instructing the S-CSCF to complete the previously unfinished re-registration process with it. Or the S-CSCF can set an identifier internally to represent the current status of the HSS, and after skipping the interaction with the HSS, the S-CSCF can set the identifier to represent the status of the HSS failure. If the S-CSCF detects that the identifier represents a failure of the HSS, it will periodically send messages to the HSS to confirm the status of the HSS. If the HSS correctly responds to the message sent by the S-CSCF, the S-CSCF continues the previously unfinished re-registration process and restores the flag to a state indicating that the HSS is not faulty. The S-CSCF may re-do the previously unfinished re-registration process with the HSS, or may continue the previously unfinished re-registration process from the previously unfinished step.

[0139] The IMS registration system provided in the embodiment of the present application enables the S-CSCF to skip the interaction with the HSS and directly return a 200 OK message to the UE when the HSS does not respond or returns an error code. It can also complete the user re-registration process when the HSS fails or is overloaded.

[0140] In one embodiment, the S-CSCF is also used to generate disaster recovery information based on the re-registration message, and send a SAR message to the HSS if the disaster recovery information does not match the disaster recovery information stored in the S-CSCF, or return a 200 OK message to the UE if the disaster recovery information matches the disaster recovery information stored in the S-CSCF.

[0141] In an embodiment of the present application, the S-CSCF internally stores disaster recovery information for all user devices that have signed contracts with it. The disaster recovery information is used to characterize the contract status of the user device. After receiving the re-registration message, the S-CSCF needs to regenerate the disaster recovery information based on the re-registration message and compare the disaster recovery information generated this time with the disaster recovery information stored in the S-CSCF to see if they are consistent. If the disaster recovery information generated this time is inconsistent with the disaster recovery information stored in the S-CSCF, the S-CSCF needs to send a SAR (Server Assignment Request) message to the HSS. The SAR message can carry the disaster recovery information generated this time, so that the HSS updates the contract information of the user device stored in the HSS according to the SAR message, so that the contract information stored in the IMS system is consistent with the actual contract information in the user device. If the disaster recovery information generated according to the re-registration message is consistent with the disaster recovery information stored in the S-CSCF, it indicates that the user's contract information stored in the IMS system is still valid. The S-CSCF does not need to interact with the HSS and can return a 200 OK message to the user device through the I-CSCF and P-CSCF.

[0142] After the S-CSCF sends the subscription information to the HSS and the HSS updates its stored subscription information, it sends an SAA (Server Assignment Answer) message to the S-CSCF. Upon receiving the SAA message, the S-CSCF determines that the HSS has successfully updated the subscription information and can then return a 200 OK message to the user device via the I-CSCF and P-CSCF. After receiving the SAA message, the S-CSCF can also update its stored disaster recovery information based on the disaster recovery information generated by the re-registration message, ensuring that the subscription information stored in all network elements of the IMS system is consistent with the actual subscription information in the user device.

[0143] In the above interaction process between the S-CSCF and the HSS, if the HSS does not respond or returns an error code, the S-CSCF may skip the interaction with the HSS and directly return a 200 OK message to the user equipment according to the above embodiment.

[0144] The IMS registration system provided in the embodiments of the present application enables the S-CSCF to interact with the HSS when it needs to update a user's subscription information. When the HSS returns an SAA message normally, it returns a 200 OK message to the UE. If the HSS does not respond or returns an error code, it skips the interaction with the HSS and directly returns a 200 OK message to the UE. Alternatively, if it does not need to update the user's subscription information, it directly returns a 200 OK message to the UE. The user re-registration process can also be completed when the HSS fails or is overloaded.

[0145] It should be understood that, although the various steps in the flowcharts involved in the various embodiments described above are displayed in sequence according to the instructions of the arrows, these steps are not necessarily executed in sequence in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order restriction on the execution of these steps, and these steps can be executed in other orders. Moreover, at least a portion of the steps in the flowcharts involved in the various embodiments described above can include multiple steps or multiple stages, and these steps or stages are not necessarily executed and completed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a portion of steps or stages in other steps.

[0146] Based on the same inventive concept, embodiments of the present application also provide an IMS registration device for implementing the aforementioned IMS registration method. The solution provided by this device is similar to the solution described in the aforementioned method. Therefore, the specific limitations of one or more IMS registration device embodiments provided below can be found in the above-described limitations of the IMS registration method and are not further elaborated here.

[0147] In one embodiment, Figure 8 As shown, an IMS registration device 800 is provided, including: an inserting module 802 and a sending module 804, wherein:

[0148] Inserting module 802, configured to insert the address of the S-CSCF into the re-registration message;

[0149] The sending module 804 is used to forward the re-registration message to the I-CSCF so that the I-CSCF identifies the address of the S-CSCF in the re-registration message and forwards the re-registration message to the address of the S-CSCF if the address of the S-CSCF exists.

[0150] The IMS registration device provided in the embodiment of the present application enables the P-CSCF to insert the address of the S-CSCF into the re-registration message and then forward the re-registration message to the I-CSCF. The I-CSCF determines whether the re-registration message carries the address of the S-CSCF. If the re-registration message includes the address of the S-CSCF, the I-CSCF obtains the address of the S-CSCF and forwards the re-registration message to the S-CSCF, so that the S-CSCF completes the subsequent re-registration process for the UE. By enabling the P-CSCF to insert the address of the S-CSCF into the re-registration message, the embodiment of the present application enables the I-CSCF to obtain the address of the HSS during the re-registration process without interacting with the HSS through the DRA signaling network, thereby reducing the resource consumption of the DRA signaling network and the HSS.

[0151] In one embodiment, the insertion module 802 is further configured to:

[0152] Insert the S-CSCF address into the new header field of the re-registration message.

[0153] In one embodiment, the insertion module 802 is further configured to:

[0154] In case of HSS and / or UDM failure, the address of the S-CSCF is inserted into a new header field of the re-registration message.

[0155] In one embodiment, the insertion module 802 is further configured to:

[0156] Check the registration status of the UE;

[0157] In the case that the UE has been registered, the address of the S-CSCF is inserted into the new header field of the re-registration message.

[0158] In one embodiment, the insertion module 802 is further configured to:

[0159] Determine a value of integrity protection, and determine that the UE is registered when the value of integrity protection is a first value, or determine that the UE is not registered when the value of integrity protection is a second value.

[0160] In one embodiment, Figure 9 As shown, an IMS registration device 900 is provided, comprising: a first receiving module 902, an identification module 904, and a first forwarding module 906, wherein:

[0161] A first receiving module 902 is configured to receive a re-registration message forwarded by the P-CSCF to the I-CSCF;

[0162] an identification module 904, configured to identify an address of an S-CSCF in the re-registration message, wherein the address of the S-CSCF is inserted into the re-registration message by the P-CSCF;

[0163] The first forwarding module 906 is configured to forward the re-registration message to the address of the S-CSCF if the address of the S-CSCF exists.

[0164] The IMS registration device provided in the embodiment of the present application enables the P-CSCF to insert the address of the S-CSCF into the re-registration message and then forward the re-registration message to the I-CSCF. The I-CSCF determines whether the re-registration message carries the address of the S-CSCF. If the re-registration message includes the address of the S-CSCF, the I-CSCF obtains the address of the S-CSCF and forwards the re-registration message to the S-CSCF, so that the S-CSCF completes the subsequent re-registration process for the UE. By enabling the P-CSCF to insert the address of the S-CSCF into the re-registration message, the embodiment of the present application enables the I-CSCF to obtain the address of the HSS or UDM without interacting with the HSS or UDM through the DRA signaling network during the re-registration process, thereby reducing the resource consumption of the DRA signaling network and the HSS or UDM.

[0165] In one embodiment, the identification module 904 is further configured to:

[0166] Identify new header fields in re-registration messages;

[0167] In a case where the new header field exists, the address of the S-CSCF is obtained from the new header field.

[0168] In one embodiment, the apparatus further comprises:

[0169] a sending module, configured to send a UAR message to the HSS if the address of the S-CSCF does not exist;

[0170] a second receiving module, configured to receive a UAA message sent by the HSS in response to the UAR message, and obtain the address of the S-CSCF from the UAA message;

[0171] The second forwarding module is configured to forward the re-registration message to the address of the S-CSCF.

[0172] In one embodiment, the first forwarding module 906 is further configured to:

[0173] When the HSS is in a normal state, a UAR message is sent to the HSS.

[0174] Each module in the above-mentioned apparatus may be implemented in whole or in part by software, hardware, or a combination thereof. Each module may be embedded in or independent of a processor in a computer device in the form of hardware, or may be stored in a memory in the computer device in the form of software, so that the processor can call and execute the operations corresponding to each module.

[0175] In one embodiment, a network element device is provided. Figure 10 A schematic diagram of the structure of a network element device provided in an embodiment of the present application. The network element may include a receiver 1001, a memory 1002, a processor 1003, at least one communication bus 1004, and a transmitter 1005. The communication bus 1004 is used to implement communication connections between components. The memory 1002 may include a high-speed RAM memory, and may also include a non-volatile storage NVM, such as at least one disk storage. The memory 1002 may store various programs for performing various processing functions and implementing the method steps of this embodiment. In this embodiment, the transmitter 1005 may be a radio frequency processing module or a baseband processing module in an access network device, and the receiver 1001 may also be a radio frequency processing module or a baseband processing module in an access network device. The transmitter 1005 and the receiver 1001 may be integrated together to form a transceiver. Both the transmitter 1005 and the receiver 1001 may be coupled to the processor 1003, and may perform receiving or transmitting actions under the instruction or control of the processor 1003.

[0176] In this embodiment, the processor 1003 is configured to insert the address of the S-CSCF into the re-registration message;

[0177] Transmitter 1005 is used to forward the re-registration message to the I-CSCF so that the I-CSCF identifies the address of the S-CSCF in the re-registration message and forwards the re-registration message to the address of the S-CSCF if the address of the S-CSCF exists.

[0178] In one embodiment, the processor 1003 is further configured to:

[0179] Insert the S-CSCF address into the new header field of the re-registration message.

[0180] In one embodiment, the processor 1003 is further configured to:

[0181] In case of HSS and / or UDM failure, the address of the S-CSCF is inserted into a new header field of the re-registration message.

[0182] In one embodiment, the processor 1003 is further configured to:

[0183] Check the registration status of the UE;

[0184] In the case that the UE has been registered, the address of the S-CSCF is inserted into the new header field of the re-registration message.

[0185] In one embodiment, the processor 1003 is further configured to:

[0186] Determine a value of integrity protection, and determine that the UE is registered when the value of integrity protection is a first value, or determine that the UE is not registered when the value of integrity protection is a second value.

[0187] In one embodiment, a network element device is provided. Figure 11 A schematic diagram of the structure of a network element device provided in an embodiment of the present application. The network element may include a receiver 1101, a memory 1102, a processor 1103, at least one communication bus 1104, and a transmitter 1105. The specific definitions of the receiver 1101, the memory 1102, the processor 1103, the communication bus 1104, and the transmitter 1105 can be referred to in the aforementioned embodiments, and will not be repeated in detail in the embodiments of the present application.

[0188] In this embodiment, the receiver 1101 is configured to receive a re-registration message forwarded by the P-CSCF to the I-CSCF;

[0189] Processor 1103 is configured to identify an address of an S-CSCF in the re-registration message, where the address of the S-CSCF is inserted into the re-registration message by the P-CSCF;

[0190] The transmitter 1105 is configured to forward the re-registration message to the address of the S-CSCF if the address of the S-CSCF exists.

[0191] In one embodiment, the processor 1103 is further configured to:

[0192] Identify new header fields in re-registration messages;

[0193] In a case where the new header field exists, the address of the S-CSCF is obtained from the new header field.

[0194] In one embodiment, the processor 1103 is further configured to control the transmitter 1105 to send a UAR message to the HSS if the address of the S-CSCF does not exist;

[0195] The receiver 1101 is further configured to receive a UAA message sent by the HSS in response to the UAR message, and obtain the address of the S-CSCF from the UAA message;

[0196] The transmitter 1105 is further configured to forward the re-registration message to the address of the S-CSCF.

[0197] In one embodiment, the processor 1103 is further configured to detect an HSS status identifier;

[0198] The processor 1103 is further configured to control the transmitter 1105 to send a UAR message to the HSS when the HSS is normal.

[0199] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the steps in the above-mentioned method embodiments are implemented.

[0200] In one embodiment, a computer program product is provided, including a computer program, which implements the steps in the above method embodiments when executed by a processor.

[0201] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties.

[0202] Those skilled in the art will appreciate that all or part of the processes in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the above-mentioned embodiments. In particular, any reference to memory, database, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The databases involved in the various embodiments provided herein may include at least one of a relational database and a non-relational database. Non-relational databases may include, but are not limited to, distributed databases based on blockchains. The processors involved in the various embodiments provided herein may be, but are not limited to, general-purpose processors, central processing units (CPUs), graphics processing units (GPUs), digital signal processors (DSPs), programmable logic devices (PLDs), data processing logic devices based on quantum computing, and the like.

[0203] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0204] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be determined by the appended claims.

Claims

1. An IMS registration method, characterized in that: Applied to a P-CSCF, the method includes: Insert the S-CSCF address into the re-registration message; The re-registration message is forwarded to the I-CSCF, so that the I-CSCF identifies the address of the S-CSCF in the re-registration message and forwards the re-registration message to the address of the S-CSCF if the address of the S-CSCF exists.

2. The method according to claim 1, characterized in that The inserting the address of the S-CSCF into the re-registration message includes: Insert the S-CSCF address into the new header field of the re-registration message.

3. The method according to claim 2, characterized in that Inserting the address of the S-CSCF into the new header field of the re-registration message includes: In case of HSS and / or UDM failure, the address of the S-CSCF is inserted into a new header field of the re-registration message.

4. The method according to claim 2, characterized in that Inserting the address of the S-CSCF into the new header field of the re-registration message includes: Check the registration status of the UE; In the case that the UE has been registered, the address of the S-CSCF is inserted into the new header field of the re-registration message.

5. The method according to claim 4, characterized in that The detecting the registration status of the UE includes: Determine a value of integrity protection, and determine that the UE is registered when the value of integrity protection is a first value, or determine that the UE is not registered when the value of integrity protection is a second value.

6. An IMS registration method, characterized in that: Applied to an I-CSCF, the method includes: receiving a re-registration message forwarded by the P-CSCF to the I-CSCF; identifying an address of an S-CSCF in the re-registration message, the address of the S-CSCF being inserted into the re-registration message by the P-CSCF; If the address of the S-CSCF exists, forward the re-registration message to the address of the S-CSCF.

7. The method according to claim 6, characterized in that The identifying the address of the S-CSCF in the re-registration message includes: Identify new header fields in re-registration messages; In a case where the new header field exists, the address of the S-CSCF is obtained from the new header field.

8. The method according to claim 6, characterized in that The method further comprises: If the address of the S-CSCF does not exist, send a UAR message to the HSS; receiving a UAA message sent by the HSS in response to the UAR message, and obtaining an address of the S-CSCF from the UAA message; The re-registration message is forwarded to the address of the S-CSCF.

9. The method according to claim 8, characterized in that The sending of the UAR message to the HSS includes: When the HSS is normal, a UAR message is sent to the HSS.

10. An IMS registration system, characterized in that: The system includes P-CSCF, I-CSCF and S-CSCF, wherein: the P-CSCF, configured to insert the address of the S-CSCF into a re-registration message, and forward the re-registration message to the I-CSCF; The I-CSCF is configured to identify the address of the S-CSCF in the re-registration message, and forward the re-registration message to the address of the S-CSCF if the address of the S-CSCF exists.

11. The system according to claim 10, wherein: The S-CSCF is used to interact with the HSS, and when the HSS has no response or the HSS returns an error code, skips the interaction with the HSS and returns a 200 OK message to the UE.

12. The system according to claim 10, wherein: The S-CSCF is further used to generate disaster recovery information based on the re-registration message, and send a SAR message to the HSS if the disaster recovery information does not match the disaster recovery information stored in the S-CSCF; or return the 200 OK message to the UE if the disaster recovery information matches the disaster recovery information stored in the S-CSCF.

13. An IMS registration device, characterized in that: Applied to a P-CSCF, the apparatus includes: An insertion module, configured to insert the address of the S-CSCF into the re-registration message; The sending module is used to forward the re-registration message to the I-CSCF, so that the I-CSCF identifies the address of the S-CSCF in the re-registration message and forwards the re-registration message to the address of the S-CSCF if the address of the S-CSCF exists.

14. An IMS registration device, characterized in that: Applied to I-CSCF, the device includes: A first receiving module is configured to receive a re-registration message forwarded by the P-CSCF to the I-CSCF; an identification module, configured to identify an address of an S-CSCF in the re-registration message, wherein the address of the S-CSCF is inserted into the re-registration message by the P-CSCF; The first forwarding module is configured to forward the re-registration message to the address of the S-CSCF if the address of the S-CSCF exists.

15. A network element device, characterized in that: including a processor and a transmitter; The processor is configured to insert the address of the S-CSCF into the re-registration message; The transmitter is configured to forward the re-registration message to the I-CSCF, so that the I-CSCF identifies the address of the S-CSCF in the re-registration message, and forwards the re-registration message to the address of the S-CSCF if the address of the S-CSCF exists.

16. A network element device, characterized in that: Includes receiver, processor and transmitter; The receiver is configured to receive a re-registration message forwarded by the P-CSCF to the I-CSCF; the processor being configured to identify an address of an S-CSCF in the re-registration message, the address of the S-CSCF being inserted into the re-registration message by the P-CSCF; The transmitter is configured to forward the re-registration message to the address of the S-CSCF if the address of the S-CSCF exists.

17. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 9 are implemented.

18. A computer program product comprising a computer program, characterized in that When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 9 are implemented.

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