WO2008125063A1 - Method, system and apparatus of called route - Google Patents

Abstract

A method, a system and an apparatus of called route are disclosed, which can insert an user agent net-element in the calling path, and route the calling request message to the user through the user agent net-element, after realizing that DSF selects a succession session to the field of CS. The method includes the following steps: After Domain Select Function DSF selecting the succession session to the field of CS, adding the correlative information that the calling request message routing to the user agent net-element in the calling request message in the calling request message of down sending to a S-CSCF; S-CSCF routing the calling requestmessage to the user agent net-element according to the correlative information, and the user agent net-element routing the calling request message to the original called user through the field of CS.

Description

 Method, system and device for called route

Technical field

 The present invention relates to the field of communications, and in particular, to a method, system and apparatus for called routing. Background technique

IMS (IP Multimedia Subsystem) is a ^{3GPP R5 / R6 (3 rd Generation} Partnership Project Release 5 / Release 6) standards defined by WCDMA (Wideband Code Division Multiple Access) network, IP (Intemet Protocol) Multimedia Subsystem, a 3G (3 ^rf Generation) The mobile network implements packet voice and packet data to provide a unified multimedia service and application target network. The IMS adopts the IP packet domain as the bearer channel for its control signaling and media transmission, and uses the Session Inition Protocol (SES) as the call control signaling. In IMS, the IMS user subscription data is centrally managed in the Home Subscriber Server (hereinafter referred to as: HSS), the service is uniformly provided by the application server AS, and the session control is controlled by the service-call session control function (Serving-Call Session). The following functions are called: S-CSCF), the two are completely separated on the network structure, and the service is triggered by the S-CSCF to the AS. The multiple ASs can work together. The user accesses the IMS through the current location proxy node proxy-proxy-Call Session Control Function (hereinafter referred to as: P-CSCF), and the session and service control are completed by the home domain service node of the registered domain, so the user The same service can always be obtained at different access points, which realizes the separation of service management, session control and bearer access, and service provision independent of access and location.

 [GRUU related background technology]

In the case of a called party, for the case where a multi-terminal shares a public user identity (IP Multimedia Public Identity; the following cartridge: IMPU), in order to prevent "SIP REQUEST" from forking to multiple terminals (UE), Internet Engineering The Task Force (Internet Engineering Task Force; hereinafter referred to as: IETF) and 3GPP introduced the globally routable user agent identifier (Globally Routable) User Agent URI; The following cartridge is called: GRUU) This is nothing to say. GRUU is a combination of the "Instance ID" of the IMPU and the UE. The "Instance ID" is a globally unique ID used to identify "UE Instance", so that the GRUU can uniquely identify a UE. Even if the IMPU is shared by multiple UEs, using the GRUU as a "REQUEST URI" can ensure that SIP messages are sent to the uniquely designated UE.

 [feature tag related background technology]

 This is an application mechanism added by the IETF to SIP signaling (refer to RFC 3840). It is used to attach various parameters after the "contact" header field to indicate various application capabilities of the terminal, such as audio capabilities, video capabilities, Mobility, supported languages, uses (commercial or personal), supported SIP methods, priorities, etc. Another mechanism is the "Caller Preferences" proposed by the IETF in RFC 3841. This mechanism is used in conjunction with the above feature tag. The calling party can specify that some called terminals should have according to the attributes of the session. The application characteristics (carried in the Accept-contact header field), or application characteristics that should not be available, allow the network to search for the most suitable terminal for connection according to the specified application capability among the multiple terminals used by the called party.

 [DSAI related introduction]

 The dynamic service activation information (Dynamic Service Activation Information; DSAI) is an identifier that identifies whether a service is activated or not. It allows the AS to dynamically set whether a service is activated or not. If no activation is required, set a service to "Inactive" through the SH interface. The HSS sets the service trigger rule (Initial Filter Criteria; the following cartridge: iFC) corresponding to the service to "Inactive", and the updated The iFC is delivered to the S-CSCF, so that the call will not be triggered to the corresponding AS. The essence of DSAI is that the AS can activate or deactivate one or some iFCs as needed to control the session routing.

 [related background of ICS]

During the evolution of the network to IMS, there will be a period of circuit-switched (hereinafter referred to as: CS) and IMS coexistence. At this time, the operator hopes that there is a control point in the network that can The domain's business is centrally controlled to reduce deployment and Manage costs and provide a consistent business experience. This centralized control point is generally in the IMS network and is implemented by the AS. That is, when the user accesses through the CS network, it also provides services for the IMS network.

 In the current VCC standard, when the domain selection entity DSF selects a CS domain connection session, it determines the routing number (CSRN) to the CS domain, and the VCC AS modifies the "Request-uri" to the routing number of the CS domain ( CS Domain Routing Number; The following cartridge is called: CSRN), so that the call is routed to the CS domain, so that the call will not be triggered to other ASs again. The specific process is shown in Figure 1, including the series of steps:

 1. The S-CSCF receives a call request message directed to the user.

 2. The S-CSCF triggers the call request message to the DSF according to the triggering rule of the iFC.

 3 ~ 4, DSF performs domain selection, selects the CS domain connection session according to its own domain selection rule, and determines CSRN.

 5. The DSF sends the call to the S-CSCF.

 6. The S-CSCF finds that the "Request-uri" is CSRN and routes the call request message to the MGCF (the interaction with the BGCF is omitted).

 7-9. The MGCF determines the MSRN according to the CSRN, and then routes the call request message to the original called user.

 After the DSF selects the CS domain connection session, it will change the Request-uri to CSRN, so that the call will be routed directly to the CS domain through the S-CSCF, but in the ICS (IMS Centlised Service) topic, it needs to be in the S-CSCF. The ICCF is inserted before the call is routed to the CS domain, so that the ICCF can participate in the control of subsequent services. Summary of the invention

The embodiment of the invention provides a method, a system and a device for routing a called party. After the DSF is selected to connect to the CS domain, the user agent network element can be inserted into the call path, and the call request message is routed to the user agent network element. user. The method for routing the called party according to the embodiment of the present invention includes: after the domain selection entity DSF selects the connection session to the CS domain, adding the call request message to the user agent network element in the call request message sent to the S-CSCF The S-CSCF routes the call request message to the user agent network element according to the related information; and the user agent network element routes the call request message to the original called user via the CS domain.

 The domain selection entity of the embodiment of the present invention includes: a domain selection unit, configured to select a connection session to the CS domain or a connection session to the PS domain; and a first adding unit, configured to: when the domain selection unit selects a connection session to the CS domain, The call request message to be delivered is added to the information related to the user agent network element, and the sending unit is configured to send the call request message processed by the first adding unit to the S-CSCF.

 The user agent network element of the embodiment of the present invention includes: a receiving unit, configured to receive a call request message;

 An obtaining unit, configured to obtain a routing number of the original called user number or the CS domain; a determining unit, configured to determine routing information according to the original called user number or the routing number of the CS domain acquired by the acquiring unit; the routing unit, configured to Determining the routing information determined by the unit, and routing the call request message to the original called user via the CS domain.

 The system of the called route of the embodiment of the present invention includes: a DSF, an S-CSCF, and a user agent network element; the DSF is configured to select a connection session to the CS domain, and add the call request message sent to the S-CSCF. Routing the call request message to related information of the user agent network element; the S-CSCF is configured to route the call request message to the user agent network element according to the related information; the user agent network element, and the call request message is sent to the CS The domain is routed to the original called user terminal.

Another called routing method in the embodiment of the present invention includes: when a user attaches in the CS domain and is not registered in the PS domain, the user agent network element triggers iFC activation to the user agent network element through the DSAI mechanism; When the CS domain connection session is selected, the call request message is sent to the S-CSCF; the S-CSCF triggers the call request message to the user agent network element according to the iFC; and the user agent network element passes the call request message to the CS The domain is routed to the original called user. In the embodiment of the present invention, after the DSF selects the connection session to the CS domain, the related information for routing the call request message to the user agent network element is added to the call request message sent to the S-CSCF, and the S-CSCF may be based on the correlation. The information is routed to the user agent network element; the user agent network element then routes the call request message to the original called user via the CS domain according to the obtained routing information. Therefore, after the DSF is selected to the CS domain connection session, the user agent network element can be inserted in the call path, and the call request message is routed to the user via the CS domain via the user agent network element, which satisfies the requirements of the ICS problem.

 In the embodiment of the present invention, when the user is attached in the CS domain and the PS domain is not registered, the user agent network element triggers the iFC activation to the user agent network element through the DSAI mechanism; after the DSF selection to the CS domain connection session is implemented, A user agent network element can be inserted in the call path, and the call request message is routed to the user via the CS domain via the user agent network element, which satisfies the requirements of the ICS subject. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flow chart of a route after an existing DSF selects a connection session to a CS domain;

 2 is a flow chart of steps of a method for called routing according to an embodiment of the present invention;

 3 is a schematic structural diagram of a domain selection entity according to an embodiment of the present invention;

 4 is a schematic structural diagram of a user agent network element according to an embodiment of the present invention;

 Figure 5 is a flowchart of Embodiment 1 of the present invention;

 6 is a flowchart of Embodiment 2 of the present invention;

 7 is a flowchart of Embodiment 3 of the present invention;

 8 is a flowchart of Embodiment 4 of the present invention;

 9 is a flowchart of Embodiment 5 of the present invention;

 FIG. 10 is a flowchart of another method for routing a called method according to an embodiment of the present invention;

Figure 11 is a flow chart of Embodiment 6 of the present invention. detailed description

 IMS is a description of 3GPP and Tispan (Telecommunications and Internet Converged Services and Protocols for Advanced Networking). In 3GPP2, there is also a similar multimedia subsystem called Multimedia Domain (hereinafter referred to as MMD), which is similar in structure to IMS. 4. The content described below obviously also applies to MMD.

 In order to implement the DSF selection to the CS domain connection session, a user agent network element can be inserted in the call path, and the call request message is routed to the user via the user agent network element.

 The embodiment of the present invention is an example in which the AS is used as a user agent network element, but the user agent network element is not limited to being placed on the AS, but may also be placed on the enhanced MSC (Mobile Switching Center).

 An embodiment of the present invention provides a method for called routing, as shown in FIG. 2, including the following steps:

 Sl l and DSF select to connect to the CS domain.

 S12. The DSF adds related information for routing the call request message to the user agent network element in a call request message sent to the S-CSCF.

 The related information may be a public service identifier of the user agent network element (Public Service Identity; the following is called: PSI); then the DSF obtains the PSI of the user agent network element, including the following steps: The DSF sends signaling to the HSS to obtain the original Calling the MSRN of the user; the user agent network element performs signaling interception, and returns the PSI of the user agent network element in the response message of the intercepted signaling; and the DSF obtains the PSI of the user agent network element from the response message. Or,

 The DSF obtains the PSI of the user agent network element from the local static configuration. Or,

The related information is the calling preference information, and the DSF obtains the calling preference information, including the following steps: When the user agent network element replaces the user registration, the user carries the "Feature tag" in the registration request message; the S-CSCF takes the user's " Feature tag" is reported to DSF, DSF will The feature tag is used as the calling preference information, that is, the calling preference information is carried in the "invite", but the calling preference information, the information corresponding to the called side is the feature tag of the called user. or,

 The related information is the GRUU of the user agent network element; the DSF obtaining the GRUU of the user agent network element includes the following steps: The user agent network element carries the "instance-id" in the registration request message when replacing the user registration; S-CSCF The GRUU is allocated to the user agent network element according to the "instance-id" in the received registration request message, and the GRUU is reported to the DSF. Or,

 The related information is the information that triggers the initial filtering rule iFC, and the S-CSCF performs iFC matching according to the related information added by the DSF in the call request message, and triggers the call request message to the user agent network element according to the matched iFC. .

 513. The S-CSCF routes the call request message to the user agent network element according to the related information.

 514. The user agent network element routes the call request message to the original called user (that is, the called user originally pointed to by the call request message) according to the obtained routing information.

 The embodiment of the present invention further provides a domain selection entity, as shown in FIG. 3, which includes: a domain selection unit 11, a first adding unit 12, and a sending unit 13; further comprising: an obtaining unit 14 and a second adding unit 15 .

 The domain selection unit 11 is used to select a CS domain connection session or a PS domain connection session.

 The obtaining unit 14 is configured to obtain related information for routing the call request message to the user agent network element, and the processing is performed by the first adding unit 12.

 The first adding unit 12 is configured to add related information for routing the call request message to the user agent network element in the call request message to be sent when the domain selection unit selects the CS domain connection session.

 The second adding unit 15 is configured to add the original called user number or the routing number of the CS domain to the call request message to be delivered.

The sending unit 13 is configured to add the first adding unit 12, or the first adding unit 12 and the second adding The call request message processed by the unit 15 is sent to the S-CSCF.

 The embodiment of the present invention further provides a user agent network element. As shown in FIG. 4, the method includes: a receiving unit 21, an obtaining unit 22, a determining unit 23, and a routing unit 24.

 The receiving unit 21 is configured to receive a call request message.

 The obtaining unit 22 is configured to obtain the routing number of the original called user number or the CS domain.

 The determining unit 23 is configured to determine routing information according to the original called user number or the routing number of the CS domain acquired by the obtaining unit 22.

 The routing unit 24 is configured to route the call request message to the original called user via the CS domain according to the routing information determined by the determining unit 23.

 The embodiment of the present invention further provides a system for called routing, including: DSF (ie, DSF in the embodiment of the present invention), S-CSCF, and user agent network element.

 The DSF is configured to select a connection session to the CS domain, and add related information for routing the call request message to the user agent network element in a call request message sent to the S-CSCF.

The S-CSCF is configured to route the call request message to the user agent network element according to the related information.

 The user agent network element is configured to, according to the obtained routing information, route the call request message to the original called user terminal via the CS domain.

 The following is specifically described by the five embodiments.

 [Embodiment 1] The PSI of the ICCF is returned by means of signaling interception, and the call request message is routed to the user through the CSRN. See Figure 5, which includes the following steps:

 1. The S-CSCF receives a call request message directed to the user.

 2. The S-CSCF triggers the call request message to the DSF according to the triggering rule of the iFC.

3. The DSF performs domain selection, according to its own domain selection rule, selects a CS domain connection session, and sends an SRI command to the HSS to obtain the mobile station roaming number of the original called user (mobile station roaming number; the following cylinder: MSRN) .

4. The ICCF performs signaling interception and returns its own PSI in the response message of the SRI message. 5. The DSF fills in the PSI of the ICCF obtained from the response message into the "Request-uri" of the call request message, and sets the routing number of the CS domain of the original called user (CS Domain).

Routing Number ; The following cartridge is called: CSRN ) (converted from MSRN) to fill in the "P-Called-Party-ID" header field of the call request message (or fill the CSRN of the original called user to "History-info" In the header field, or in other header fields, then the call request message is sent to the S-CSCF.

 6. The S-CSCF routes the call request message to the ICCF according to the PSI of the ICCF in the "Request-uri" of the call request message.

 7. The ICCF determines the CSRN of the original called user, and fills the CSRN into the "Request-uri" of the call request message, and then delivers the call request message to the S-CSCF.

 8. The S-CSCF finds that the "Request-uri" in the call request message is CSRN, and routes the call request message to the MGCF (the interaction with the BGCF is omitted).

 9. The MGCF determines the MSRN based on the CSRN and then routes the call request message to the original called user.

 [Embodiment 2] The PSI of the ICCF is statically configured in the DSF, and the call request message is routed to the user through the CSRN. See Figure 6, which includes the following steps:

 1. The S-CSCF receives a call request message directed to the user.

 2. The S-CSCF triggers the call request message to the DSF according to the triggering rule of the iFC.

3. The DSF performs domain selection, selects a CS domain connection session according to its own domain selection rule, and fills the configured ICCF PSI into the "Request-uri" of the call request message, and the number of the original called user. Fill in the message to the "P-Called-Party-ID" header field of the call request message (or fill in the number information of the original called user into the "History-info" header field, or other header fields), and then place the call. The request message is delivered to the S-CSCF.

 4. The S-CSCF routes the call request message to the ICCF according to the PSI of the ICCF in the "Request-uri" of the call request message.

5. The ICCF determines the CSRN of the original called user, and fills in the CSRN to the call request. In the "Request-uri" of the message, the call request message is then sent to the S-CSCF.

 6. The S-CSCF finds that the "Request-uri" in the call request message is CSRN, and routes the call request message to the MGCF (the interaction with the BGCF is omitted).

 7. The MGCF determines the MSRN based on the CSRN and then routes the call request message to the original called user.

 [Embodiment 3] The call request message is routed to the ICCF through the calling preference mechanism, and the call request message is routed to the user through the CSRN. Referring to FIG. 7, the following steps are included: 1. The S-CSCF receives a call request message directed to the user (the "Request-uri" of the call request message carries the original called subscriber number information).

 2. The S-CSCF triggers the call request message to the DSF according to the triggering rule of the iFC.

3. The DSF performs domain selection, selects a connection session to the CS domain according to its own domain selection rule, and then fills in the information of the CS connection session in the Accept-Contact header field of the call request message Accept-Contact: Access-type=CS . And in the call request message

The routing number ( CSRN ) of the CS domain carried in the "P-Called-Party-ID" header field or the "History-info" header field. The call request message is then sent to the S-CSCF.

 4. The S-CSCF finds that the connection of the ICCF meets the requirements according to the requirements in the Accept-Contact of the call request message. (When the ICCF replaces the user registration, the access network type has been reported, so that the S-CSCF records the user at the ICCF. The registration is in the CS domain, so that the ICCF is located according to Access-type=CS, and the call request message is routed to the ICCF.

 5, ICCF directly puts the "P-Called-Party-ID" header field of the call request message or

The CSRN carried in the "History-info" header field is filled in the "Request-uri" of the call request message, and then the call request message is sent to the S-CSCF; or carried in the "Request-uri" according to the call request message. The original called subscriber number information determines the CSRN, and the CSRN is filled in the "Request-uri" of the call request message, and then the call request message is sent to the S-CSCF.

6. The S-CSCF finds that the "Request-uri" in the call request message is CSRN. Called to MGCF (omitting the interaction with BGCF).

 7. The MGCF determines the MSRN based on the CSRN and then routes the call to the original called user. In this embodiment, the ICCF is required to report that the access network type of the user is CS by using the Feature tag mechanism.

 In step 3 of Figure 8, the DSF can also fill in the information that rejects the PS access, such as:

Reject-Contact: Access-type=PS. Information equivalent to the CS connection session Accept-Contact: Access-type=CS.

 In this embodiment, the AS is used as the user agent network element. When the user agent network element is in the VMSC, the above steps 5-7 can be omitted, and the VMSC directly delivers the call to the user.

 [Embodiment 4] The call request message is routed to the ICCF through the GRUU. Referring to Figure 8, the following steps are included:

 1. The S-CSCF receives a call request message directed to the user.

 2. The S-CSCF triggers the call request message to the DSF according to the triggering rule of the iFC.

3. The DSF performs domain selection, selects a CS domain connection session according to its own domain selection rule, and fills the GCF of the ICCF into the "Request-uri" of the call request message, and puts the number information of the original called user. Go to the "P-Called-Party-ID" header field or the "History - info" header field. The call request message is then sent to the S-CSCF.

 4. The S-CSCF locates the connection to the ICCF according to the GRUU in the "Request-uri" of the call request message, and then routes the call request message to the ICCF.

 5. The ICCF finds the number information of the original called user from the "P-Called-Party-ID" header field of the call request message or the "History - info" header field, and changes the "Request-uri" to the original called party. The user's number information is then sent to the MGCF.

 6. The MGCF routes the call to the user according to the normal call flow.

In this embodiment, the ICCF is required to logically generate an "instance-id" when the user is registered instead, so that the S-CSCF can use the "instance-id" to allocate a GRUU to the ICCF, and report the GRUU to the DSF. . In this embodiment, the AS is used as the user agent network element. When the user agent network element is in the VMSC, the above steps 5-6 can be omitted, and the VMSC directly delivers the call to the user.

 [Embodiment 5] The information added by the DSF triggers the iFC, routes the call request message to the ICCF according to the iFC, and routes the call request message to the user through the CSRN. See Figure 9, which includes the following steps:

 1. The S-CSCF receives a call request message directed to the user. (The "Request-uri" of the call request message carries the original called subscriber number information).

 2. The S-CSCF triggers the call request message to the DSF according to the triggering rule of the iFC.

3. The DSF performs domain selection, selects a CS domain connection session according to its own domain selection rule, and adds in the Accept-Contact header field of the call request message, or the "History-info" header field or other header fields. The S-CSCF is instructed to route the call request message to the trigger information of the iFC of the ICCF, and then the call request message is sent to the S-CSCF. And carrying the CS domain routing number (CSRN) in the "P-Called-Party-ID" header field or the "History-info" header field of the call request message. The call request message is then sent to the S-CSCF.

 4. The S-CSCF routes the call request message to the ICCF according to the triggered iFC.

 5. The ICCF determines the CSRN according to the original called subscriber number information carried in the "Request-uri" of the call request message, or directly from the "P-Called-Party-ID" header field or the "History-info" header field. The CSRN is obtained, and the CSRN is filled in the "Request-uri" of the call request message, and then the call request message is sent to the S-CSCF.

 6. The S-CSCF finds that "Request-uri" is CSRN and routes the call request message to

MGCF (omitting the interaction with BGCF).

 7. The MGCF determines the MSRN based on the CSRN and then routes the call request message to the original called user.

 The embodiment of the present invention further provides another called routing method, as shown in FIG. 10, including the following steps:

S21. When the user is attached in the CS domain, the user agent network element is triggered by the DSAI mechanism. The iFC activation of the user agent network element.

 S22. When the DSF selects to connect to the CS domain, the call request message is sent to the S-CSCF. S23. The S-CSCF triggers the call request message to the user agent network element according to the iFC. S24. The user agent network element routes the call request message to the original called user via the CS domain according to the obtained routing information.

 The following is specifically described by way of an embodiment.

 [Embodiment 6] The call request message is routed to the ICCF through the DSAI mechanism, and the call request message is routed to the user through the CSRN. Referring to Figure 11, the following steps are included:

 1. The S-CSCF receives a call request message directed to the user.

 2. The S-CSCF triggers the call request message to the DSF according to the triggering rule of the iFC.

3. The DSF performs domain selection, selects a connection session to the CS domain according to its own domain selection rule, and can carry in the "P-Called-Party-ID" header field or the "History-info" header field of the call request message. The routing number (CSRN) of the CS domain is then sent to the S-CSCF.

 4. The S-CSCF triggers the call request message to the ICCF according to the triggering rule of the iFC.

 5. The ICCF obtains the MSRN of the original called user through the HSS/HLR to VLR query, determines the CSRN of the original called user according to the MSRN, and fills the CSRN into the "Request-uri" of the call request message, and then puts the call. The request message is delivered to the S-CSCF. You can also use the "P-Called-Party-ID" header field of the call request message or the routing number (CSRN) of the CS domain carried in the "History-info" header field.

 6. The S-CSCF finds that the "Request-uri" is CSRN and routes the call request message to the MGCF (the interaction with the BGCF is omitted).

 7. The MGCF determines the MSRN based on the CSRN and then routes the call request message to the original called user.

In this embodiment, the ICCF is required to use the DSAI mechanism to activate the iFC routed to the ICCF. Then send it to the S-CSCF for use in step 4. When the user logs out in the CS domain, the call request message does not need to be routed to the ICCF. At this time, the user agent network element will trigger the iFC to the user agent network element to deactivate through the DSAI mechanism.

 In step 5 of the embodiment, the ICCF obtains the MSRN of the original called user through the HSS/HLR to VLR query, and then determines the CSRN of the original called user according to the MSRN, and the same applies in Embodiments 1 to 5. Embodiments 1 to 5 The manner in which the ICCF obtains routing information is also applicable in this embodiment.

 In summary, in the embodiment of the present invention, after the DSF selects the CS domain connection session, the DSF sends a call request message sent to the S-CSCF to the related information of the user agent network element, so S The CSCF may route the call request message to the user agent network element according to the related information; then the user agent network element routes the call request message to the original called user via the CS domain according to the obtained routing information. Therefore, after the DSF selects the CS domain connection session, the user agent network element can be inserted in the call path, and the call request message is routed to the user via the CS domain via the user agent network element, which satisfies the requirements of the ICS problem.

 Further, the first to fifth embodiments described above respectively describe different situations in which the call request message is routed to the related information of the user agent network element.

 In the embodiment of the present invention, when the user is attached in the CS domain and is not registered in the PS domain, the user agent network element triggers the iFC activation to the user agent network element through the DSAI mechanism; after the DSF selection to the CS domain connection session is implemented, A user agent network element can be inserted in the call path, and the call request message is routed to the user via the CS domain via the user agent network element, which satisfies the requirements of the ICS subject.

 It should be noted that the above embodiments are only for explaining the technical solutions of the present invention, and are not intended to be limiting; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those skilled in the art that: The technical solutions described in the foregoing embodiments are modified, or some of the technical features are equivalently replaced. The modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

Claim A method for called routing, characterized in that the method comprises the following steps:  After the domain selection entity DSF selects to the circuit switched CS domain connection session, the related information for routing the call request message to the user agent network element is added to the call request message sent to the service-call session control function entity S-CSCF;  The S-CSCF routes the call request message to the user agent network element according to the related information;  The user agent network element routes the call request message to the original called user via the CS domain.  2. The method according to claim 1, wherein the related information is a public service identifier PSI of a user agent network element;  The DSF obtains the PSI of the user agent network element and includes the following steps: The DSF sends signaling to the home subscriber server HSS to obtain the mobile station roaming number MSRN of the original called user; the user agent network element performs signaling interception, and the response of the intercepted signaling Returning the PSI of the user agent network element in the message; and obtaining, by the DSF, the PSI of the user agent network element from the response message; or  The DSF obtains the PSI of the user agent network element from the local static configuration.  3. The method according to claim 1, wherein the related information is referred to as a preference information;  The DSF obtains the calling preference information, including the following steps: The user agent network element carries the user's Feature tag in the registration request message when the user registration is replaced; the S-CSCF sends the user's Feature tag to the DSF, and the DSF uses the Feature tag as the Feature tag. Caller preference information.  4. The method according to claim 1, wherein the related information is a globally routable user agent identifier GRUU pointing to a user agent network element; The DSF obtains the GRUU of the user agent network element, including the following steps: The user agent network element carries the instance-id in the registration request message when the user registration is replaced; the S-CSCF is the user according to the instance-id in the received registration request message. The proxy network element allocates GRUU, and the GRUU Reported to the DSF.  5. The method according to claim 1, wherein the S-CSCF performs iFC matching according to the related information added by the DSF in the call request message, and triggers the call request message to the user agent according to the matched iFC. Network element.  The method according to claim 2 or 4, wherein the related information is carried in a Request-uri of a call request message.  The method according to claim 6, wherein the DSF further carries the original called subscriber number or CS domain routing number in the call request message sent to the S-CSCF;  The user agent network element searches the call request message for the original called user number or the routing number of the CS domain, and determines routing information accordingly.  8. The method according to claim 3, wherein the related information is carried in an Accept-contact header field or a Reject-contact header field of a call request message.  The method according to claim 5 or 8, wherein the DSF carries the routing number of the CS domain in the call request message sent to the S-CSCF;  The user agent network element obtains the routing number of the CS domain in the call request message, and determines routing information accordingly.  10. A domain selection entity, comprising:  a domain selection unit, configured to select a connection session to the CS domain or to a PS domain connection session; a first adding unit, configured to add, in the call request message to be delivered, when the domain selection unit selects a connection session to the CS domain The call request message is routed to related information of the user agent network element;  a sending unit, configured to send a call request message processed by the first adding unit to  S-CSCF.  The entity of claim 10, further comprising: An obtaining unit, configured to acquire the related information, and handed to the first adding unit for processing. The entity according to claim 10, further comprising: a second adding unit, configured to add a routing number of the original called user number or the CS domain to the call request message to be delivered.  13. A user agent network element, comprising:  a receiving unit, configured to receive a call request message;  An obtaining unit, configured to obtain a routing number of an original called user number or a CS domain;  a determining unit, configured to determine routing information according to the original called user number or the routing number of the CS domain acquired by the acquiring unit;  And a routing unit, configured to route the call request message to the original called user via the CS domain according to the routing information determined by the determining unit.  14. A system for called routing, comprising: a DSF, an S-CSCF, a user proxy network element;  The DSF is configured to select a connection session to the CS domain, and add related information for routing the call request message to the user agent network element in a call request message sent to the S-CSCF;  An S-CSCF, configured to route the call request message to the user agent network element according to the related information;  The user agent network element routes the call request message to the original called user terminal via the CS domain.  15. A method for routing a called party, comprising the steps of:  When the user attaches in the CS domain, the user agent network element activates the iFC triggered to the user agent network element through the dynamic service activation information DSAI mechanism;  When the DSF selects to connect to the CS domain, the call request message is sent to the S-CSCF.  The S-CSCF triggers the call request message to the user agent network element according to the iFC; and the user agent network element routes the call request message to the original called user via the CS domain.  The method according to claim 15, wherein when the user logs out in the CS domain, the user agent network element deactivates the iFC triggered to the user agent network element by using a DSAI mechanism. 17. The method of claim 15, wherein the DSF is sent to the S-CSCF The call request message carries the routing number of the CS domain;  The user agent network element obtains the original called user number or the routing number of the CS domain in the call request message, and determines routing information accordingly.