WO2011020390A1 - Number conversion method and service continuity application server - Google Patents

Abstract

The invention provides a number conversion method, which includes: a calling user initiates a call in a circuit switched domain; the core network of the circuit switched domain sends a session invitation message to the Service Continuity Application Server (SC AS) to which the calling user belongs; and after receiving the session invitation message, the SC AS compares the calling user number in the session invitation message with the user data of the calling user, and sets the calling user number in the session invitation message based on the comparison result, then forwards the session invitation message to the called user. The invention also provides a Service Continuity Application Server. In the invention, by converting the calling user number, an appropriate calling user number can be sent to the called user based on the demand.

Description

 Number conversion method and business continuity application server

Technical field

 The present invention relates to the field of communications, and in particular, to an IP multimedia subsystem number conversion method and a service continuity application server.

Background technique

 IP (Internet Protocol, Network Interconnection Protocol) Multimedia Subsystem (IMS) is an IP-based network architecture proposed by the 3rd Generation Partnership Project (3GPP). An open and flexible business environment that supports multimedia applications and provides users with rich multimedia services.

 IMS is an IP-based telecommunications network architecture, which is independent of the access technology. In addition to providing services for packet access networks such as GPRS (General Packet Radio Service) and WLAN (Wireless Local Area Network). It can also provide services for mobile worm networks such as GSM (Global System for Mobile communications) and UMTS (Universal Mobile Telecommunications System).

 Mobile cellular networks such as GSM and UMTS use circuit switching technology, called Circuit Switched (CS) domain, to provide users with basic voice services and supplementary services based on voice services. When the CS domain accesses the IMS, it evolves into an access mode, and the service is completely provided by the IMS. This technology is called IMS Centralized Service (ICS).

 User Equipment (UE) maintains voice continuity in PS domain and CS domain handover. The technology that guarantees this continuity is called IMS Voice Call Continuity (VCC).

Figure 1 is a system reference frame diagram of an IMS session transfer. The entire framework includes a User Equipment (UE) 101, a Mobile Switch Center (MSC) 102, and a Media Gateway Control Function (MGCF) 103. Media Gateway (MGW) 104, Proxy Call Session Control Function (P-CSCF) 105, query call session control function

(Interrogating Call Session Control Function, referred to as I-CSCF) 106. Home Subscriber Server (HSS) 107, Serving Call Session Control Function (S-CSCF) 108, service Continuity application server

Service Continuity Application Server (SC AS for short) 109. Service Control Point (SCP) 110.

 The SC AS 109 provides a multimedia service continuity server, a multimedia service server, etc., and can provide services such as multimedia service continuity and multimedia services for users.

 The SCP 110 is an intelligent network service control network element, and mainly performs third-party service control on the traditional circuit domain service through the intelligent service.

 The Correlation MSISDN (C-MSISDN) is a number that is uniquely associated with a session for session transfer to implement session transfer in the IMS number sharing scenario. In the IMS domain, the associated number corresponds to the user's private user ID. The associated number is usually brought to the SC AS by the S-CSCF when the user registers with the third party, or the SC AS obtains the third-party registration from the HSS according to the user's private user ID. When the user initiates the session, the SC AS anchors the session with the association number. When the user initiates the inter-domain call transfer, the SC AS associates the anchor session with the association number in the newly established session request and switches it.

 Figure 2 is a schematic diagram of session transfer in a number sharing scenario. The number 123 is shared by the UE 1 and the UE 2 at the same time. When the UE 1 initiates a session with the remote UE 3 by using the number 123, the UE 2 also uses the number 123 to initiate a session with the remote UE 4, and the UE 2 may move due to the time. Decided to switch the current session to the CS domain.

 Figure 3 is a flowchart of a session transfer in a number sharing scenario. Both UE 1 and UE 2 are VCC users. The process includes the following steps:

 301, UE 1 and UE 3 have a communication session in the packet domain, and the service control signaling of the session service is anchored on the SC AS of the IMS network, the number of UE 1 is 123, and the number of UE 3 is 444. Wherein the SC AS anchors the session using the association number 111 of the UE 1;

302. The UE 2 and the UE 4 also have a communication session in the packet domain, and the session service The service control signaling is also anchored on the SC AS of the IMS network, the number of the UE 2 is shared with the UE 1, the same as 123, and the number of the UE 4 is 555, wherein the SC AS anchors the session using the association number 222 of the UE 2 ;

 303. At this time, the UE 2 may transfer the current session to the circuit domain due to the air quality of the air interface or the user moving.

 304. The UE 2 performs a standard attach procedure on the target circuit domain network.

 305. After the UE 2 is successfully attached, send a call setup request message to the circuit domain network, where the message includes the user identity identifier and the called number. The called number is set to the session transfer number (STN) of the terminal static configuration;

 The STN is mainly used for routing and identifying the session transfer. When the circuit domain core network receives the call setup request message, according to the STN, the session request is routed to the SC AS of the home UE 2 home network. After receiving the session request, the SC AS receives the session request. The STN judges that the session request is for session switching, replacing the original session (see steps 306-311).

 306. The MSC Server (Mobile Switching Center Server) receives the call setup request message of the UE 2, and sends an address initial message to the UE 2 home domain IMS network MGCF according to the analysis of the STN number, where the message includes the called number and the calling party. The number, where the called number is STN, and the calling number is set to the associated number of UE 2.

 There are two ways for the MSC Server to obtain the associated number. In one step, the HSS sends the associated number (C-MSISDN) as the user number to the MSC Server. In another method, the MSC Server initiates the call. The intelligent service replaces the associated number (C-MSISDN) with the calling number of the user;

 307. After receiving the initial address message, the MGCF sends a SIP (Session Initiation Protocol) session invitation message, and the target address in the message is STN, and is sent to the SC AS.

 308. The SC AS receives the session invitation message, determines, according to the target address in the message, that the session invitation message is a session transfer request message, and finds the previously anchored according to the calling number in the message, that is, the association number of the UE 2. Packet domain session;

309. The SC AS updates the remote UE 4 media peer IP address and port address to the IP address and port number of the new session. 310. After the remote update succeeds, the SC AS releases the original packet domain session.

 311. The SC AS returns a session success message to the UE 2, indicating that the session transfer is successful.

 In the above scenario, if UE 1 initiates a normal call initiation process, there will be a problem, as shown in FIG. 4, the process includes:

 401. The UE 1 initiates an attach procedure on the CS network.

 The UE 1 initiates a call in the CS domain, and sends a call setup message to the MSC Server, where the called number carried in the message is the UE 2 number;

 403. The MSC Server receives the call setup message of the UE 1, triggers the intelligent service, and obtains an IP Multimedia Routing Number (IMRN) from the SC AS of the user home, where the message carries the called number (ie, the number of the UE 2) ).

 404. After obtaining the IMRN, the MSC Server sends an initial address message to the home IMS network according to the IMRN, where the message carries the calling number and the called number, where the calling number is the associated number of UE1, and the called number is IMRN;

 405. After receiving the initial address message, the MGCF sends a Session Initiation Protocol (SIP) session invitation message, and the target address in the message is IMRN, and is sent to the SC AS.

 406. The SC AS receives the session invitation message, and according to the IMRN in the message, associates the original called number in step 403, and sets the called number in the session invitation message to the original called number, and the SC AS sends the called UE to the called UE. The UE 2) forwards the session invitation, and the calling number in the session invitation message forwarded to the called UE (ie, UE 2) is the associated number;

 407, session response.

 In the above process, in step 406, the calling number in the session invitation message forwarded by the SC AS to the UE 2 is an associated number, and the associated number is a number of an associated session generated within the network, and the associated number and the user number are still different. According to the above steps, the calling number received by the called UE is an associated number, which affects the calling number display of the called user and the blacklist of the calling party.

 In the above scenario, UE 1 also has a problem when it is called. As shown in Figure 5, the process includes:

501, UE 3 sends a session invitation message to UE 1, where the target address in the message is UE 1 user number 123; 502-504, the S-CSCF receives the session invitation message, and according to the target address in the message, determines that the circuit domain user forwards the session invitation message to the MGCF;

 505. The MGCF sends an initial address message to the target MSC Server according to the analysis of the called number 123, where the called number is 123.

 After receiving the initial address message, the MSC Server searches for the called party according to the called number 123. However, in some cases, as shown in step 306, the user number saved by the MSC Server is the user association according to the C-MSISDN obtaining mode 1. The number (C-MSISDN) 111, at this time, the MSC Server considers that the user of the number 123 is not within its jurisdiction, rejects the call, and thus cannot page the user.

Summary of the invention

 The technical problem to be solved by the present invention is to provide a number conversion method and a service continuity application server, which solves the problem of VCC user call and termination calls in a number sharing scenario.

 In order to solve the above technical problem, the present invention provides a number conversion method, including: a calling user initiates a call in a circuit domain; and a circuit domain core network sends a session invitation message to a service continuity application server (SC) to which the calling user belongs. And the SC AS receives the session invitation message, compares the calling number in the session invitation message with the user data of the calling user, and sets the session invitation message according to the comparison result. After the calling number, the session invitation message is forwarded to the called user.

 Preferably, the method may further include: after receiving the session invitation message, the SC AS acquires the calling user from a home subscriber server to which the calling user belongs according to a calling number in the session invitation message. User data, or, after the SC AS receives the IP multimedia routing number request sent by the mobile switching center server in the circuit domain core network, according to the calling number in the IP multimedia routing number request, from the calling user The belonging home subscriber server acquires user data of the calling subscriber.

Preferably, the foregoing method may further include the following: the user data includes a public user identification example table of the calling user, or a public user identification example table and an associated number including the calling user, or includes the main The public user identification list, the associated number, and the display number set by the calling user at the home subscriber server. Preferably, the foregoing method may further have the following feature: the step of setting, by the SC AS, the calling number in the session invitation message according to the comparison result: if the user data includes a display number and the session invitation message The calling number is not the display number, and the SC AS sets the display number as the calling number in the session invitation message.

 Preferably, the foregoing method may further have the following feature: the public user identification example table includes a default number;

 The step of setting, by the SC AS, the calling number in the session invitation message according to the comparison result includes: if the user data does not include a display number and the calling number in the session invitation message is not included in the public user In the identification example table, the calling number is an association number, and the SC AS sets the default number in the public user identification example table as the calling number in the session invitation message.

 Preferably, the foregoing method may further have the following feature: the step of setting, by the SC AS, the calling number in the session invitation message according to the comparison result: if the user data includes a display number and the session invitation message The calling number is the display number, or if the user data does not include a display number and the calling number in the session invitation message is included in the public user identification example table, the SC AS reserves the session. The calling number in the invitation message.

 The present invention also provides a number conversion method, including: a calling user initiates a call to a called user in a circuit domain; and the SC AS receives a session invitation message of the calling user, where the session invitation message is The destination address is compared with the number currently used by the called user. After the destination address in the session invitation message is set according to the comparison result, the session invitation message is forwarded to the called user.

 Preferably, the method may further include: the SC AS acquiring, from the home subscriber server to which the called user belongs, the number currently used by the called user according to the destination address in the session invitation message.

Preferably, the foregoing method may further have the following feature: the step of setting, by the SC AS, the destination address in the session invitation message according to the comparison result: when the destination address in the session invitation message is currently used by the called user When the number is different, the SC AS sets the destination address in the session invitation message to the number currently used by the called user; when the destination address in the session invitation message is related to the number currently used by the called user At the same time, the SC AS reserves the destination address in the session invite message. The present invention further provides a service continuity application server (SC AS ), configured to: when receiving a session invitation message sent by a circuit domain core network, the calling number in the session invitation message and the calling user The user data is compared, and after the calling number in the session invitation message is set according to the comparison result, the session invitation message is forwarded to the called user.

 Preferably, the SC AS is further configured to: after receiving the session invitation message, acquire, according to the calling number in the session invitation message, the calling user from a home subscriber server to which the calling user belongs User data, or, after receiving the IP multimedia routing number request sent by the mobile switching center server in the circuit domain core network, according to the calling number in the IP multimedia routing number request, from the home subscriber server to which the calling user belongs Obtaining user data of the calling user.

 Preferably, the SC AS is further configured to: when the user data includes a display number and the calling number in the session invitation message is not the display number, set the display number as the session invitation message. The calling number in .

 Preferably, the SC AS is configured to not include a display number in the user data, and a calling number in the session invitation message is not included in a public user identity instance table in the user data, and the calling party When the number is an associated number, the default number in the public user identification example table is set as the calling number in the session invitation message.

 Preferably, the SC AS is configured to include a display number in the user data, and the calling number in the session invitation message is the display number, or the user data does not include a display number and the When the calling number in the session invitation message is included in the public user identity instance table in the user data, the calling number in the session invitation message is retained.

 The present invention also provides a Service Continuity Application Server (SC AS), which is configured to: when a calling user initiates a call to a called user in a circuit domain, and the SC AS receives a session invitation message of the calling user, The destination address in the session invitation message is compared with the number currently used by the called user. After the destination address in the session invitation message is set according to the comparison result, the session invitation message is forwarded to the called user.

Preferably, the SC AS is further configured to acquire, according to the destination address number in the session invitation message, the number currently used by the called user from the home subscriber server to which the called user belongs. Preferably, the SC AS is configured to set a destination address in the session invitation message to be currently used by the called user when the destination address in the session invitation message is different from the number currently used by the called user. The number of the session invitation message is retained when the destination address in the session invitation message is the same as the number currently used by the called user.

 With the present invention, in the scenario where the UE shares the number, the SC AS can solve the calling and terminating problems by converting the number.

BRIEF abstract

 Figure 1 is a system reference frame diagram of an IMS session transfer;

 2 is a schematic diagram of session transfer in an IMS number sharing scenario;

 Figure 3 is a flow chart of session transfer in an IMS number sharing scenario;

 4 is a flowchart of a call origination in an IMS number sharing scenario in the prior art;

 5 is a flow chart of a terminal call in an IMS number sharing scenario in the prior art;

 6 is a flowchart of an embodiment of a call number conversion in an IMS number sharing scenario according to the present invention; and FIG. 7 is a flowchart of a call forwarding number conversion embodiment in an IMS number sharing scenario according to the present invention.

Preferred embodiment of the invention

 The technical solution of the present invention will be described in more detail below with reference to the accompanying drawings and embodiments.

 The present invention provides a number conversion method, including: a calling user initiates a call in a circuit domain, and a circuit domain core network sends a session invitation message to the SC AS to which the calling user belongs, and the SC AS sends the session invitation message The calling number is compared with the user data of the calling user, and the calling number in the session invitation message is set according to the comparison result, and then the session invitation message is forwarded to the called user.

After receiving the session invitation message, the SC AS acquires the user data of the calling user from the home subscriber server to which the calling user belongs according to the calling number in the session invitation message; or, the SC After receiving the IP multimedia routing number request sent by the mobile switching center server, the AS obtains the calling number in the IP multimedia routing number request from the attribution to which the calling user belongs. The user server acquires user data of the calling user.

 The user data includes a public user identification example table of the calling user, or includes a public user identification example table and an associated number of the calling user, or includes a public user number example table and an associated number of the calling user. And a display number set by the calling user at the home subscriber server, where the public subscriber number list includes a default number.

 The SC AS compares the calling number in the session invitation message with the user data of the calling user, and the step of setting the calling number in the session invitation message according to the comparison result includes: if the user data The display number is included in the session invitation message, and the calling number is not the display number, and the SC AS sets the display number as the calling number in the session invitation message;

 If the user data does not include a display number and the calling number in the session invitation message is not included in the public subscriber number list and the calling number is an associated number, the SC AS will be a public subscriber number. The default number in the table is set to the calling number in the session invitation message;

 If the user data includes a display number and the calling number in the session invitation message is the display number, or if the user data does not include a display number and the calling number in the session invitation message includes In the public subscriber number example table, the SC AS reserves the calling number in the session invitation message.

 The present invention also provides a number conversion method, including: a calling user initiates a call to a called user in a circuit domain, and the SC AS receives a session invitation message of the calling user, and the purpose of the session invitation message The address is compared with the number currently used by the called user. After the destination address in the session invitation message is set according to the comparison result, the session invitation message is forwarded to the called user.

 The step of setting, by the SC AS, the destination address in the session invitation message according to the comparison result includes:

 When the destination address in the session invitation message is different from the number currently used by the called user, the SC AS sets the destination address in the session invitation message to the number currently used by the called user; for example, When the number currently used by the called user is an associated number, the SC AS sets the destination address in the session invitation message as the associated number of the called user.

When the destination address in the session invitation message is the same as the number currently used by the called user, the SC AS reserves the destination address in the session invitation message. After receiving the session invitation message, the SC AS obtains the number currently used by the called user from the home subscriber server to which the called user belongs according to the destination address number in the session invitation message.

 Embodiment 1

 FIG. 6 is a flow chart of the number translation start call signaling in the IMS number sharing scenario according to the first embodiment of the present invention. The SC AS receives the session invitation message, and determines whether the calling number in the message needs to be replaced. If the replacement is required, the calling number in the message is replaced and then forwarded to the called party. The process includes:

 601. The UE 1 initiates an attach procedure on the CS network.

 602. The UE 1 initiates a call in the CS domain, and sends a call setup message to the MSC Server, where the called number carried in the message is the UE 2 number.

 603. The MSC Server receives the call setup message of the UE 1, triggers the intelligent service, and sends an IP Multimedia Routing Number (IMRN) request message to the SC AS of the user, where the message carries the called number (ie, UE 2). Number) and calling number;

 604. After obtaining the IMRN, the MSC Server sends an initial address message to the user's home IMS network according to the IMRN, where the message carries the calling number and the called number, where the calling number is the associated number of the UE 1, and the called number is the IMRN;

 605. After receiving the initial address message, the MGCF sends a SIP session invitation message, and the target address in the message is IMRN, and is sent to the SC AS.

 606. The SC AS receives the session invitation message, and according to the IMRN in the message, the original called number in step 503 is associated, and the called number in the session invitation message is set as the original called number, and the SC AS obtains the session invitation message. The calling number, and according to the calling number, obtains the public User Identities (PUI) example table, the associated number, and the display number set by the user in the HSS from the HSS to which the user belongs.

 The display number refers to a user identifier that is displayed in the two formats of the user terminal and the Tel URI when the user calls other users, and the PUI example table further includes a default number.

 607. The HSS returns user data to the SC AS.

608. After obtaining the user data, the SC AS compares the calling number in the session invitation message with the user data, and sets the calling number in the session invitation message according to the result. The step includes: The SC AS determines whether the user data includes a display number:

 If the user data includes the display number, the SC AS continues to determine whether the calling number in the received session invitation message is the same as the display number. If not, the SC AS sets the display number as the calling number in the session invitation message. ; if they are the same, retain the calling number in the session invitation message;

 If the user data does not include the display number, the SC AS continues to determine whether the calling number in the received session invitation message is included in the PUI instance table. If yes, the calling number is not replaced, that is, the calling party in the session invitation message is retained. If the calling number is not included in the PUI example table, and the calling number is the associated number, the SC AS sets the default number in the PUI example table as the calling number in the session invitation message;

 609. The SC AS forwards a session invitation message to the remote UE (ie, UE 2).

 610, session response.

 In another embodiment of the present invention, the SC AS may also request the user data of the calling user from the HSS according to the calling number in the request message after receiving the IP multimedia routing number request message in step 603.

 In another embodiment of the present invention, the user data requested by the SC AS to the HSS may include only one user number and an associated number. When the calling number in the session invitation message is an associated number, the SC AS directly directly invites the session invitation message. The calling number in is set to the user number.

 Embodiment 2

 FIG. 7 is a flow chart of number-switching termination call signaling in an IMS number sharing scenario according to Embodiment 2 of the present invention.

 The SC AS receives the termination call invitation message, and obtains the associated number of the called user and the number currently used by the user according to the called number in the message, and if the currently used number is the associated number, SC AS The destination address in the received terminal call message is changed to the associated number. The process includes:

 701, UE 3 calls UE 1 through the subscriber number of UE1;

 702. The I-CSCF/S-CSCF forwards the session invitation message to the SC AS.

 703. The SC AS obtains the number currently used by the called user from the HSS to which the called user belongs according to the destination address in the session invitation message, and obtains the associated number of the called user from the HSS.

704. The HSS returns the number currently used by the called user, and may also return the associated number of the called user. 705. After obtaining the currently used number, the SC AS compares the destination address in the session invitation message with the current number used by the called user, and sets a destination address in the session invitation message according to the comparison result.

 The step includes: when the destination address in the session invitation message is different from the number currently used by the called user, the SC AS sets the destination address in the session invitation message to the number currently used by the called user. For example, when the number currently used by the called user is an associated number, the SC AS sets the destination address in the session invitation message as the associated number of the called user; when the destination address and the location in the session invitation message are When the number currently used by the called user is the same, the SC AS reserves the destination address in the session invitation message.

 In this embodiment, the number currently used by the user is an associated number, and the destination address in the session invitation message is set as the associated number;

 706-707, after the conversion is successful, the SC AS sends the converted session invitation message to the called side network;

 708. The called side MSC Server receives the initial address message, finds the location of the user according to the user association number, and initiates a call setup request message to the UE1.

 709. The called UE 1 connects to the session and makes a call with the UE 3.

 The present invention also provides a service continuity application server, where the service continuity application server is configured to, when receiving a session invitation message sent by the circuit domain core network, the calling number in the session invitation message and the The user data of the calling user is compared, and after setting the calling number in the session invitation message according to the comparison result, the session invitation message is forwarded to the called user.

 The SC AS is further configured to: after receiving the session invitation message, obtain, according to the calling number in the session invitation message, user data of the calling user from a home user server to which the calling user belongs Or, after receiving the IP multimedia routing number request sent by the mobile switching center server in the circuit domain core network, obtaining, according to the calling number in the IP multimedia routing number request, from the home subscriber server to which the calling user belongs User data of the calling user.

The SC AS is configured to: when the user data includes a display number and the calling number in the session invitation message is not the display number, set the display number as the main in the session invitation message Calling a number; the display number is not included in the user data, and the calling number in the session invitation message is not included in the public user identification example table and the calling number is an associated number Setting the default number in the public user identification example table as the calling number in the session invitation message; including the display number in the user data, and the calling number in the session invitation message is the display number Or, if the user data does not include the display number and the calling number in the session invitation message is included in the public user identity instance table, the calling number in the session invitation message is retained.

 The present invention also provides a service continuity application server, the service continuity application server is configured to initiate a call to a called user in a circuit domain at a calling user, and the SC AS receives a session invitation message of the calling user. And comparing the destination address in the session invitation message with the number currently used by the called user, and after setting the destination address in the session invitation message according to the comparison result, forwarding the session invitation message to the called user.

 The SC AS is configured to set a destination address in the session invitation message to a number currently used by the called user, when the destination address in the session invitation message is different from the number currently used by the called user. When the destination address in the session invitation message is the same as the number currently used by the called user, the destination address in the session invitation message is reserved.

 The SC AS is further configured to obtain, according to the destination address number in the session invitation message, the number currently used by the called user from the home subscriber server to which the called user belongs.

 It is a matter of course that the invention may be embodied in various other forms and modifications without departing from the spirit and scope of the invention.

Industrial applicability

 The number conversion method and the service continuity application server provided by the present invention can transmit the calling number to the called user as needed, and can solve the problem of the VCC user calling and ending in the number sharing scenario. Call the question.

Claims

Claim  1. A method for number conversion, comprising:  The calling user initiates a call in the circuit domain;  The circuit domain core network sends a session invitation message to the service continuity application server (SC AS ) to which the calling user belongs;  The SC AS receives the session invitation message, compares the calling number in the session invitation message with the user data of the calling user, and sets the calling number in the session invitation message according to the comparison result. And forwarding the session invitation message to the called user.  2. The method of claim 1 further comprising:  After receiving the session invitation message, the SC AS acquires the user data of the calling user from the home subscriber server to which the calling user belongs according to the calling number in the session invitation message, or the SC After receiving the IP multimedia routing number request sent by the mobile switching center server in the core network of the circuit domain, the AS obtains the primary user from the home subscriber server to which the calling user belongs according to the calling number in the IP multimedia routing number request. Call the user's user data.  The method according to claim 1 or 2, wherein the user data includes a public user identification example table of the calling user, or a public user identification example table and an associated number including the calling user, or The public user identification example table of the calling user, the associated number, and the display number set by the calling user at the home subscriber server.  4. The method according to claim 3, wherein the step of setting, by the SC AS, the calling number in the session invitation message according to the comparison result comprises: if the user data includes a display number and the session invitation message The calling number in the call is not the display number, and the SC AS sets the display number as the calling number in the session invitation message.  5. The method of claim 3, wherein  The public user identification example table includes a default number; The step of setting, by the SC AS, the calling number in the session invitation message according to the comparison result includes: if the user data does not include a display number and the calling number in the session invitation message is not included in the public user In the identification example table, the calling number is an association number, and the SC AS sets the default number in the public user identification example table as the calling number in the session invitation message. 6. The method of claim 3, wherein  The step of setting, by the SC AS, the calling number in the session invitation message according to the comparison result includes: if the user data includes a display number and the calling number in the session invitation message is the display number, or If the user data does not include a display number and the calling number in the session invitation message is included in the public user identity instance table, the SC AS reserves the calling number in the session invitation message.  7. A method for number conversion, comprising:  The calling user initiates a call to the called user in the circuit domain;  The service continuity application server (SC AS ) receives the session invitation message of the calling user, compares the destination address in the session invitation message with the number currently used by the called user, and sets the session invitation according to the comparison result. After the destination address in the message, the session invitation message is forwarded to the called user.  8. The method of claim 7 further comprising:  The SC AS acquires the number currently used by the called user from the home subscriber server to which the called user belongs according to the destination address in the session invitation message.  The method according to claim 7 or 8, wherein the step of setting, by the SC AS, the destination address in the session invitation message according to the comparison result comprises: when the destination address in the session invitation message is related to the When the number currently used by the user is different, the SC AS sets the destination address in the session invitation message to the number currently used by the called user; when the destination address in the session invitation message is current with the called user When the used numbers are the same, the SC AS reserves the destination address in the session invite message.  10. A Business Continuity Application Server (SC AS), set to:  When the session invitation message sent by the circuit domain core network is received, the calling number in the session invitation message is compared with the user data of the calling user, and the calling number in the session invitation message is set according to the comparison result. Afterwards, the session invitation message is forwarded to the called user. The service continuity application server according to claim 10, wherein the SC AS is further configured to: after receiving the session invitation message, according to a calling number in the session invitation message from the main Calling the home subscriber server to which the user belongs to obtain the user data of the calling user, or After receiving the IP multimedia routing number request sent by the mobile switching center server in the core network of the circuit domain, acquiring the calling party from the home subscriber server to which the calling user belongs according to the calling number in the IP multimedia routing number request User's user data.  The service continuity application server according to claim 10, wherein the SC AS is configured to include a display number in the user data and a calling number in the session invitation message is not the display number And setting the display number to the calling number in the session invitation message.  13. The business continuity application server according to claim 10, wherein  The SC AS is configured to not include a display number in the user data, and the calling number in the session invitation message is not included in a public user identity instance table in the user data, and the calling number is associated When the number is used, the default number in the public user identification list is set as the calling number in the session invitation message.  14. The business continuity application server according to claim 10, wherein  The SC AS is configured to include a display number in the user data, and the calling number in the session invitation message is the display number, or the user data does not include a display number and the session invitation message When the calling number in the public subscriber identity list in the user data is included, the calling number in the session invitation message is retained.  15. A Business Continuity Application Server (SC AS), set to:  When the calling user initiates a call to the called user in the circuit domain, the SC AS compares the destination address in the session invitation message with the current number used by the called user when receiving the session invitation message of the calling user. After the destination address in the session invitation message is set according to the comparison result, the session invitation message is forwarded to the called user.  The service continuity application server according to claim 15, wherein the SC AS is further configured to acquire, according to a destination address number in the session invitation message, a home subscriber server to which the called user belongs Call the number currently used by the user.  The business continuity application server according to claim 15 or 16, wherein the SC The AS is configured to set, when the destination address in the session invitation message is different from the number currently used by the called user, the destination address in the session invitation message as the number currently used by the called user; When the destination address in the session invitation message is the same as the number currently used by the called user, the destination address in the session invitation message is reserved.