WO2007019799A1

WO2007019799A1 - Method and system for accessing an ims and the ims

Info

Publication number: WO2007019799A1
Application number: PCT/CN2006/002076
Authority: WO
Inventors: Yanfei Yang; Hua Huang
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2005-08-16
Filing date: 2006-08-16
Publication date: 2007-02-22
Also published as: CN1917457A; CN100493011C

Abstract

A method for accessing an IMS includes setting more than one S-CSCFs in the IMS, each of the S-CSCFs supporting a kind of access type(201); A terminal informing the IMS its own access technology adopted while sending a registration request to the IMS(202); The IMS determining the access type belonging to the access technology adopted currently by the terminal to determine the S-CSCF supporting the access type of the terminal(203); The terminal accessing the IMS via the S-CSCF(204). A system of accessing IMS includes a terminal and an IMS. In addition, an IMS includes P-CSCF, I-CSCF, HSS and S-CSCF. Via simplifying the functions of a single S-CSCF, it avoids degradation of the service controlling capability of the S-CSCF, confliction of the terminals adopting the different access type while accessing the same S-CSCF, and wasting of the resource of the interface for terminal re-transmitting message because of the overtime of the message responding, and also decreasing the access load of a single S-CSCF so as to improve the efficiency of the terminal accessing the IMS when the IMS supports variable kinds of access types and to facilitate the development of variable services.

Description

Method, system and internet protocol multimedia subsystem for accessing internet protocol multimedia subsystem

The present invention relates to the field of access technologies, and in particular, to a method, a system for accessing an Internet Protocol multimedia subsystem, and an Internet Protocol Multimedia Subsystem. Background of the invention

The Internet Protocol Multimedia Subsystem (IMS) is a subsystem of the Third Generation Partnership Project (3GPP) proposed in the R5 version of the standard to support IP multimedia services. The IMS mainly includes: a call session control function (CSCF), a media gateway control function, a media gateway, a media resource function control part, a media resource function processing part, and an egress gateway control function. The CSCF is the core entity of the IMS. It includes the Proxy CSCF (P-CSCF), the Query CSCF (I-CSCF, ), and the Serving CSCF (S-CSCF). The P-CSCF is the first step for the terminal to contact the IMS. The CSCF provides an entry from the terminal to the IMS home domain, and the S-CSCF completes the session control function for the terminal. At the same time, the IMS also shares the Home Subscriber Server (HSS) with the circuit switched domain and the packet switched domain, and the HSS stores data related to the terminal and the service.

The core features of IMS are based on Session Initiation Protocol (SIP) and independence from access technologies. Currently, IMS proposed by 3GPP only supports 2G and 3G mobile access methods, and cannot support other access methods such as fixed access mode, etc., which cannot fully utilize the role of IMS SIP-based common platform.

In the Next Generation Network (NGN) framework, terminals and access networks are various, and the core network based on SIP sessions is only IMS-type. Therefore, to achieve IMS, access to itself by using different access methods. When the terminal provides services, it needs IMS in the network framework and network function. Various access methods are fully supported in terms of energy, quality of service (QoS) and security. At present, the relevant functional models, message flows and protocols of fixed broadband access IMS (FBI) are proposed in the 3GPP Technical Report (TR) 24.819 νθ.2.0.

According to the idea of network convergence, terminals using different access modes access the IMS through the same IMS entity, that is, one IMS entity supports multiple access modes at the same time. Before accessing the IMS, the terminal needs to initiate a registration process with the IMS to obtain the address information of the S-CSCF required for accessing the IMS. FIG. 1 is a sequence diagram of the message flow of the user equipment (UE) registering in the IMS, as shown in the figure. As shown in Figure 1, the main steps include:

Steps 101 to 102: The UE initiates a registration (Register) request to the P-CSCF, where the request message carries the registration identity of the UE and the IMS home domain name of the UE; and the P-CSCF according to the IMS home domain name of the UE carried in the registration request message, The entry of the IMS home domain of the UE is parsed: the address of the I-CSCF, and a registration request is forwarded to the I-CSCF, where the registration request message carries the UE registration identity.

Step 103: After receiving the registration request, the I-CSCF sends a User Authorization Request (UAR) message to the HSS, where the UAR message carries the UE registration identity to notify the HSS to confirm whether the UE has subscribed to the IMS service.

Generally, the I-CSCF itself stores the HSS address; if it is not saved, it obtains the HSS address from the SLF according to its own subscription relationship location function (SLF) address.

Step 104: After receiving the UAR message, the HSS returns a User Authorization Answer (UAA) message to the I-CSCF. If the HSS determines that the UE has subscribed to the IMS service according to the UE registration identity, the UAA message carries the UE registration identity and the address information of the S-CSCF selected by the HSS for the UE.

Step 105: After receiving the UAA message, the I-CSCF forwards the registration request to the S-CSCF pointed to by the S-CSCF address information carried in the UAA message according to the address information of the S-CSCF carried in the UAA message, where the registration request message is carried. The UE registers its identity. Steps 106-107: After receiving the registration request, the S-CSCF sends a server allocation request (SAR) message to the HSS, where the SAR message carries the UE registration identity and related service information of the S-CSCF; after receiving the SAR message, the HSS sends the message to the HSS. The S-CSCF returns a server allocation response (SAA) message, and the SAA message carries the UE registration identity, and the HSS saves the related service information of the S-CSCF carried in the SAR message.

Steps 108 to 110: After receiving the SAA message, the S-CSCF forwards the 200 response (OK) message carrying the UE registration identity and the S-CSCF address information to the P-CSCF through the I-CSCF, and the P-CSCF receives the 200 response. After the message, the 200 response message carrying the S-CSCF address information is sent to the UE.

After receiving the 200 response message, the UE saves the address information of the S-CSCF carried in the 200 response message, and then accesses the IMS through the S-CSCF pointed to by the S-CSCF address information carried in the 200 response message.

It can be seen from the above process that in the IMS registration process, the HSS may allocate the same S-CSCF to terminals that use different access modes to access the IMS. Therefore, terminals using different access modes may share the same S-CSCF. Access to IMS, that is, the S-CSCF needs to support different access methods, which has the following disadvantages:

1. The service control capability of the S-CSCF is degraded. Since various access technologies have their own characteristics, for example, when a fixed terminal using a fixed access method accesses the IMS, the interactive SIP message may not be compressed, and the mobile terminal using the mobile access method must access the IMS. The SIP messages that are exchanged are compressed, etc. Therefore, there is a difference in the processing of the IMS access terminals that are accessed in different manners. The S-CSCF is the core entity of the IMS. It is responsible for the session management and call control of the terminal. When the S-CSCF supports multiple access modes at the same time, its functions will become more and more complicated, which will inevitably make the S-CSCF service. Control ability is declining.

Second, affecting the development of certain services by IMS. The difficulty of accessing the IMS by terminals with different access modes is different, which will cause the access of the terminal to compete and cause some terminal access. There are more IMSs, and other types of terminal access are less, which affects the development of certain services by IMS. For example, it is relatively easy for a fixed terminal to access the IMS, but at the same time it consumes much more bandwidth than the mobile terminal. Therefore, accessing too many fixed terminals in an IMS home domain is likely to exhaust the load capacity of the S-CSCF. Therefore, when the mobile terminal interacts with the IMS, the message response is slow, and the message is continuously resent after the timeout, which not only makes the IMS mobile service difficult to carry out, but also resends the message to waste air interface resources. Summary of the invention

The present invention provides a method, system, and IMS for accessing an IMS to improve access efficiency when the IMS supports multiple access modes simultaneously.

In order to achieve the above object, the technical solution of the present invention is achieved as follows:

A method for accessing an IMS, where the method sets one or more S-CSCFs in the IMS, and each S-CSCF supports an access method, including:

A. The terminal initiates a registration request to the IMS, and informs the leg of the access technology currently used by itself;

After receiving the registration request, the IMS determines an access mode to which the access technology currently used by the terminal belongs, and determines an S-CSCF that supports the terminal access, and returns the address information of the S-CSCF to the terminal;

C. The terminal receives the address information of the S-CSCF, and accesses the IMS through the S-CSCF. The access modes supported by the S-CSCF are: a mobile access mode, a fixed access mode, or a wireless local area network access mode.

The mobile access method includes: 3GPP-Global System for Mobile Communications Enhanced Radio Access Network (GERAN), 3GPP-Universal Mobile Telecommunications System Terrestrial Radio Access Network (UTRAN) - Frequency Division Duplex Mode (FDD), 3GPP- One or any combination of four access technologies: UTRAN-Time Division Duplex Mode (TDD), 3GPP-Wideband Code Division Multiple Access (CDMA) 2000. The fixed access modes include: asymmetric digital subscriber loop (ADSL), ADSL2, ADSL2+, rate adaptive DSL, symmetric DSL, high speed DSL, HDSL2, single pair high speed DSL, ultra high speed DSL, integrated service digital network DSL ten One or any combination of the access technologies.

The wireless local area network access method includes: one or a combination of two types of access technologies: International Institute of Electrical and Electronics Engineers (IEEE) 802.11a. IEEE 802.11b.

The method further includes: the HSS in the IMS storing the correspondence between the address information of each S-CSCF and the access mode supported by the S-CSCF, and storing the correspondence between each access mode and the access technology included therein;

Step B: The IMS determines that an S-CSCF supporting terminal access includes:

The HSS finds the access mode to which the access technology currently used by the terminal belongs in the corresponding relationship between the access mode and the access technology included in the HSS, and then supports the address information of each S-CSCF saved by itself. For the correspondence between the access modes, an S-CSCF that supports the access mode to which the access technology currently used by the terminal belongs is selected.

The terminal informing the IMS that the access technology currently used by the terminal includes: The terminal notifies the IMS by the access technology currently used by the terminal in the access type field of the access network information message header of the registration request message.

The step A includes:

The terminal initiates a registration request to the I-CSCF in the IMS through the P-CSCF in the IMS, and notifies the I-CSCF of the access technology currently used by the terminal;

The step B includes:

After receiving the registration request and the access technology currently used by the terminal, the I-CSCF sends the access technology currently used by the terminal to the HSS, and the HSS is required to allocate an S-CSCF to the terminal.

B2. The HSS determines the access technology to which the access technology belongs according to the access technology currently used by the terminal. In the mode, then determine an S-CSCF that supports the access mode, and then return the address information of the S-CSCF to the I-CSCF;

B3. After receiving the returned address information, the I-CSCF forwards the registration request to the S-CSCF pointed to by the address information.

B4. After receiving the registration request, the S-CSCF returns its own related service information to the HSS, and after receiving the response message returned by the HSS, returns the address information of its own to the terminal through the I-CSCF and the P-CSCF.

Step 1: The I-CSCF sends the access technology currently used by the terminal to the HSS. The I-CSCF sends a user authorization request to the HSS carrying a parameter describing the access technology currently used by the terminal.

The parameters describing the access technology currently used by the terminal are: an access network type parameter that matches the Diameter protocol attribute value to the parameter access type.

A system for accessing an IMS, the system comprising: a terminal and an IMS, wherein:

The terminal is configured to notify the IMS of the access technology currently used by the IMS when the registration request is initiated to the IMS, and access the IMS according to the S-CSCF address information sent by the IMS;

The IMS is configured to save the correspondence between the access technology and the access mode and the correspondence between the S-CSCF address information and the access mode, determine the access mode to which the access technology sent by the terminal belongs, and the access mode The address information of the corresponding S-CSCF is sent to the terminal.

An IMS, the IMS includes: a P-CSCF, an I-CSCF HSS, and an S-CSCF, where: a P-CSCF, configured to send a registration request of an access technology currently used by the terminal to the I- to the I- The CSCF sends the S-CSCF address information sent by the I-CSCF to the terminal;

The I-CSCF is configured to send the access technology currently used by the terminal sent by the P-CSCF to the HSS, and send a registration request to the S-CSCF according to the address information of the S-CSCF sent by the HSS; send the S-CSCF The S-CSCF address information is sent to the P-CSCF;

The HSS is configured to determine the access according to an access technology currently used by the terminal sent by the I-CSCF. The access mode to which the technology belongs, and the determined address information of the S-CSCF supporting the access mode is sent to the I-CSCF; and the S-CSCF related service information sent by the S-CSCF is saved;

The S-CSCF is configured to send the related service information to the HSS according to the registration request sent by the I-CSCF, and send the own address information to the I-CSCF.

Compared with the prior art, the present invention sets one or more S-CSCFs in the IMS, and each S-CSCF supports an access mode; when the terminal initiates a registration request to the IMS, the terminal simultaneously notifies the IMS of the current use. Access technology; after receiving the registration request, the IMS determines the access mode to which the access technology belongs, further determines an S-CSCF that supports the access of the terminal, and notifies the terminal of the address information of the S-CSCF, after which the terminal Accessing the IMS through the S-CSCF, the function of the single S-CSCF is simplified, the S-CSCF service control capability is reduced, and the terminal accessing the IMS by using different access technologies is prevented from accessing the same S-CSCF. The generated conflict avoids the waste of the air interface resources caused by the retransmission of the message due to the message response timeout, and also reduces the access load of the single S-CSCF, thereby improving the terminal accessing the IMS when the IMS supports multiple access modes. The efficiency is beneficial to IMS to carry out various businesses. BRIEF DESCRIPTION OF THE DRAWINGS

1 is a sequence diagram of a message flow of a UE in a IMS in the prior art; FIG. 2 is a flowchart of a terminal accessing an IMS according to the present invention;

3 is a message flow diagram of a specific embodiment of a UE registering in an IMS according to the present invention;

4 is a system diagram of a terminal accessing an IMS provided by the present invention;

FIG. 5 is a schematic structural diagram of an IMS provided by the present invention. Mode for carrying out the invention

The core idea of the invention is: to set more than one S-CSCF in the IMS, and each The S-CSCF supports an access method; the terminal initiates a registration request to the IMS, and notifies the IMS of the access technology currently used by the IMS; after the IMS receives the registration request, according to the access technology and the access mode currently used by the terminal, Corresponding relationship of the access technology, determining an access mode to which the access technology belongs, further determining an S-CSCF supporting the terminal access, and returning the address information of the S-CSCF to the terminal, after which the terminal can pass the S-CSCF Access The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

2 is a flow chart of the terminal accessing the IMS provided by the present invention. As shown in FIG. 2, the specific steps are as follows:

Step 201: Set more than one S-CSCF in the IMS, and each S-CSCF supports an access mode.

The access modes can be divided into: mobile access mode, fixed access mode, and wireless LAN access mode. The mobile access method includes an access technology: 3GPP-Global System for Mobile Communications Enhanced Radio Access Network (GERAN), 3GPP-Universal Mobile Telecommunications System Terrestrial Radio Access Network (UTRAN)-Frequency Division Duplex Mode (FDD) ), 3GPP-UTRAN-Time Division Duplex Mode (TDD), 3GFP-Wideband Code Division Multiple Access (CDMA) 2000, etc. The fixed access method includes access technologies: Asymmetric Digital Subscriber Loop (ADSL), ADSL2, ADSL2+, Rate Adaptive DSL (RADSL), Symmetric DSL (SDSL), High Speed DSL (HDSL), HDSL2, Single Pair High Speed DSL (G.SHDSL), Ultra High Speed DSL (VDSL), Integrated Services Digital Network DSL (IDSL), etc., Wireless The LAN access mode includes access technologies: International Institute of Electrical and Electronics Engineers (IEEE) 802.11a, IEEE 802.11b, etc.

In an actual application, for an S-CSCF that supports an access mode, the access mode supported by the S-CSCF may include one or more of the access technologies included in the access mode described above. Any combination of species.

Step 202: The terminal initiates a registration request to the IMS, and notifies the IMS itself to adopt the current request. Access technology.

Step 203: After receiving the registration request, the IMS determines the access mode to which the access technology belongs according to the access technology currently used by the terminal and the corresponding relationship between the access mode and the access technology included in the access mode, thereby determining a supporting terminal. The accessed S-CSCF returns the address information of the S-CSCF to the terminal.

Step 204: After receiving the address information of the S-CSCF, the terminal accesses the IMS through the S-CSCF pointed to by the address information.

The process of the UE accessing the IMS through the S-CSCF is the same as the prior art.

FIG. 3 is a message flow diagram of a specific embodiment of a UE registered in an IMS according to the present invention. As shown in FIG. 3, the specific steps are as follows:

Step 301: The UE initiates a registration request to the P-CSCF, where the request message carries: an access type of the access network information (P-Access-Network-Info) header used to describe the access technology currently used by the UE (Access -Type) field, the registered identity of the UE, and the name of the IMS home domain.

The Access-Type field of the P-Access-Network-Info header is an optional field in the prior art, and is a mandatory field in the present invention.

Step 302: After receiving the registration request, the P-CSCF parses the entry of the IMS home domain of the UE according to the IMS home domain name of the UE carried in the registration request message: Query the address of the CSCF (I-CSCF), and The -CSCF forwards the registration request, which carries the access type field and the UE registration identity.

Step 303: After receiving the registration request, the I-CSCF sends a UAR message to the HSS, where the message carries the UE registration identity and an access network type (Access-Network-Type) parameter describing the access technology currently used by the UE, where The access type parameter matches the Diameter protocol attribute value pair (AVP) parameter: access type (Access-Type).

Adding an Access-Network-Type parameter to the UAR message is proposed by the present invention. Generally, the I-CSCF itself stores the HSS address; if it is not saved, it obtains the HSS address from the SLF according to its saved SLF address.

Step 304: After receiving the UAR message, the HSS determines that the UE has subscribed to the IMS service, and then according to the access technology currently used by the UE carried by the UAR message, and the corresponding relationship between the access mode saved by the UE and the access technology it contains. Determining the access mode to which the access technology belongs, thereby selecting an S-CSCF supporting the UE access, and then returning a UAA message to the I-CSCF, where the UAA message carries the UE registration identity and the HSS is the S-CSCF selected by the UE. Address information.

Here, the HSS itself stores the correspondence between each access method and the access technology included in the access method, and the correspondence between the address information of each S-CSCF and the access mode supported by the S-CSCF.

Step 305: After receiving the UAA message, the I-CSCF forwards the registration request to the S-CSCF pointed to by the S-CSCF address information carried in the UAA message according to the address information of the S-CSCF carried in the UAA message, where the registration request message is carried. The UE registers its identity.

Step 306: After receiving the registration request, the S-CSCF sends a SAR message to the HSS, where the SAR message carries the UE registration identity and related service information of the S-CSCF.

Step 307: After receiving the SAR message, the HSS returns an SAA message to the S-CSCF, where the SAA message carries the UE registration identity, and the HSS saves the related service information of the S-CSCF carried in the SAR message.

Steps 308~310: After receiving the SAA message, the S-CSCF will carry it through the I-CSCF.

The 200 response message of the UE registration identity and the S-CSCF address information is forwarded to the P-CSCF. After receiving the 200 response message, the P-CSCF sends a 200 response message carrying the S-CSCF address information to the UE.

After receiving the 200 response message, the UE saves the address information of the S-CSCF carried in the 200 response message, and then can be pointed by the S-CSCF address information carried in the 200 response message. The S-CSCF accesses the IMS.

4 is a system composition diagram of a terminal accessing an IMS provided by the present invention. As shown in FIG. 4, the method mainly includes: a terminal 41 and an IMS 42, where:

The terminal 41 is configured to notify the IMS 42 of the access technology currently used by the IMS 42 when the registration request is initiated to the IMS 42, and access the IMS 42 according to the S-CSCF address information sent by the IMS 42.

IMS42: a correspondence between the access mode and the access technology included in the access mode, and the correspondence between the address information of the S-CSCF and the access mode supported by the S-CSCF, and received by the receiving terminal 41. In the access technology, the access mode to which the access technology belongs is determined, and the S-CSCF address information corresponding to the access mode is determined, and the address information of the S-CSCF is sent to the terminal 41.

FIG. 5 is a schematic structural diagram of an IMS provided by the present invention. As shown in FIG. 5, the method mainly includes: P-CSCF5 K I-CSCF52, HSS53, and S-CSCF54, where:

The P-CSCF 51 is configured to receive a registration request of the IMS home domain name, the UE registration identity, and the access technology currently used by the UE, and parse the address of the I-CSCF according to the IMS home domain name of the UE. And forwarding, to the I-CSCF 52, a registration request that carries the UE registration identity and the access technology currently used by the UE; after receiving the 200 response message sent by the I-CSCF 52 that carries the UE registration identity and the S-CSCF address information, The UE sends a 200 response message carrying the S-CSCF address information.

The I-CSCF 52 is configured to send, according to the registration request sent by the P-CSCF 41, a UAR message carrying the UE registration identity and the access technology currently used by the UE to the HSS 53; and the address information of the S-CSCF carried in the UAA message returned by the HSS 53 And forwarding the registration request carrying the UE registration identity to the S-CSCF 54; forwarding the 200 response message sent by the S-CSCF 54 and carrying the UE registration identity and the S-CSCF address information to the P-CSCF 51.

The HSS53 is configured to determine, according to the UE registration identity carried in the UAR message sent by the I-CSCF 52, the UE that is carried by the UE according to the UAR message after the UE subscribes to the IMS service. The access technology currently used and the corresponding relationship between the access mode saved by itself and the access technology included therein determine the access mode to which the access technology belongs, and then save according to itself.

Corresponding relationship between the S-CSCF address information and the access mode supported by the S-CSCF, determining an S-CSCF supporting UE access, and then returning to the I-CSCF 52 an address carrying the UE registration identity and the S-CSCF determined for the UE The UAA message of the information; after receiving the SAR message sent by the S-CSCF 54, returning the SAA message carrying the UE registration identity to the S-CSCF 54 and saving the same

Relevant service information of the S-CSCF carried in the SAR message.

The S-CSCF 54 is configured to: after receiving the registration request sent by the I-CSCF 52, send a SAR message carrying the UE registration identity and the related service information of the S-CSCF to the HSS 53; after receiving the SAA message returned by the HSS 53, the S-CSCF 54 A 200 response message having the UE registration identity and S-CSCF address information is sent to the I-CSCF 52.

The above is only the embodiment of the process and method of the present invention, and is not intended to limit the present invention. Any modifications, equivalents, improvements, etc. made within the spirit and principles of the present invention should be included in the present invention. Within the scope of protection.

Claims

Claim

A method for accessing an Internet Protocol Multimedia Subsystem IMS, wherein one or more service call session control functions CSCF are set in an IMS, and each service CSCF supports an access mode, and the method includes:

A. The terminal initiates a registration request to the IMS, and simultaneously informs the IMS of the access technology currently used by itself;

After receiving the registration request, the IMS determines an access mode to which the access technology currently used by the terminal belongs, and determines a service CSCF that supports the terminal access, and returns the address information of the service CSCTF to the terminal;

C. The terminal receives the address information of the CSCF of the service, and accesses the IMS through the CSCF.

The method according to claim 1, wherein the access mode supported by the serving CSCF is: a mobile access mode, a fixed access mode, or a wireless local area network access mode.

3. The method according to claim 2, wherein the mobile access mode comprises: a third generation partnership plan 3GPP-global mobile communication system enhanced wireless access network GERAN, 3GPP-universal mobile communication system terrestrial wireless One or any combination of four access technologies: access network UTRAN-frequency division duplex mode FDD, 3GPP-UTRAN-time division duplex mode TDD, 3GPP-wideband code division multiple access CDMA2000.

The method according to claim 2, wherein the fixed access mode comprises: asymmetric digital subscriber loops ADSL, ADSL2, ADSL2+, rate adaptive DSL, symmetric DSL, high speed DSL, HDSL2, single pair One or any combination of ten high-speed DSL, ultra-high-speed DSL, and integrated service digital network DSL access technologies.

The method according to claim 2, wherein the wireless local area network access method comprises: one or a combination of two types of access technologies: IEEE802.11a and IEEE802.11b.

The method according to claim 1, wherein the method further comprises: a home subscriber server HSS in the IMS storing a correspondence between address information of each serving CSCF and an access mode supported by the UE, and saving each access The correspondence between the mode and the access technology it contains;

The IMS determines that the serving CSCF supporting the terminal access includes: finding the access mode to which the access technology currently used by the terminal belongs, and then corresponding to the access mode supported by the CSCF of each service according to its own saved access mode. Relationship, select a service CSCF that supports the access mode to which the access technology currently used by the terminal belongs.

The method according to claim 1, wherein the terminal informing the IMS that the access technology currently used by the terminal includes:

The terminal notifies the IMS of the access control currently used by the terminal in the access type field of the access network information header of the registration request message.

The method of claim 1, wherein the step A comprises: the terminal initiating a registration request to the querier CSCF in the IMS through the proxy CSCF in the IMS, and simultaneously informing the CSCF of the access technology currently used by the CSCF;

The step B includes:

After receiving the registration request and the access technology currently used by the terminal, the CSCF sends the access technology currently used by the terminal to the HSS, and the HSS is required to allocate a monthly CSCF to the terminal.

B2, the HSS determines the access mode to which the access technology belongs according to the access technology currently used by the terminal, and then determines a service CSCF that supports the access mode, and then returns the address information of the serving CSCF to the query CSCF;

B3. After receiving the returned address information, the CSCF forwards the registration request to the serving CSCF pointed to by the address information. B4. After receiving the registration request, the serving CSCF returns its own related service information to the HSS, and after receiving the response message returned by the HSS, returns its own address information to the terminal by querying the CSCF and the proxy CSCF.

The method of claim 8, wherein the step S1, the querying the CSCF, to send the access technology currently used by the terminal to the HSS includes:

The query CSCF sends a user authorization request carrying the parameters describing the access technology currently used by the terminal to the HSS.

The method according to claim 9, wherein the parameter describing the access technology currently used by the terminal is: an access network type parameter matching a Diameter protocol attribute value to a parameter access type.

11. A system for accessing an IMS, the system comprising: a terminal and an IMS, wherein:

12. An IMS, characterized in that the IMS comprises: a proxy CSCF, a query CSCF. HSS and a service CSCF, wherein:

The CSCF is used to send the registration request of the access technology currently used by the terminal to the querying CSCF, and send the CSCF address information sent by the CSCF to the terminal.

The CSCF is used to send the access technology currently used by the terminal sent by the proxy CSCF to the HSS, and send a registration request to the serving CSCF according to the address information of the serving CSCF sent by the HSS; the CSCF address information of the service sent by the serving CSCF Sent to the agent CSCF; The HSS is configured to determine, according to the access technology currently used by the terminal sent by the CSCF, the access mode to which the access technology belongs, and send the determined address information of the serving CSCF that supports the access mode to the query CSCF; Service CSCF related service information sent by CSCF;

The service CSCF is configured to send a self-related service information to the HSS according to the registration request sent by the CSCF, and send the address information to the CSCF.