WO2006099813A1

WO2006099813A1 - A method , system and number transform entity for establishing a call route from circuit switched network to ims network

Info

Publication number: WO2006099813A1
Application number: PCT/CN2006/000500
Authority: WO
Inventors: Yajuan Wu
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2005-03-25
Filing date: 2006-03-24
Publication date: 2006-09-28

Abstract

A method, system and number transform entity for establishing a call route from circuit switched network to IMS network, in which a coincidence relation is set between a tel-URI constructed by a E.164 number of a UE and the SIP-URI of the UE in the HSS of the IMS network, the method further comprises: A, after receiving the call carrying the E.164 number of the called UE transmitted by the calling UE in the circuit switched network, the MGCF in the IMS network constructs and sends a SIP message carrying the tel-URI constructed by the E.164 number of the called UE to the I-CSCF; B, the I-CSCF queries the coincidence relation set by the HSS and obtains the SIP-URI corresponding to the tel-URI constructed by the E.164 number of the called UE carried by the SIP message, transmits the SIP message to the called UE according to the SIP-URI, the called UE implements the SIP session negotiation process with the calling UE, then the call ends. The method and entity provided by the invention implement the establishment of the call route from the circuit switched network to the IMS network.

Description

Method, system and number conversion entity for establishing circuit switching network to IMS network call routing

Technical field

The present invention relates to a technique for establishing call routing in an Internet Protocol Multimedia Subsystem (IMS) network, and more particularly to a method, system and number translation entity for establishing a call routing network to an IMS network call route. Background of the invention

With the development of broadband networks, mobile communications are not limited to traditional voice communications, but can also combine multiple media services such as audio, video, pictures and text. A variety of media services can meet the diverse needs of user equipment (UE) by combining data services such as presence, short message, web browsing, location information, push service (PUSH), and file sharing.

Driven by various data service applications, standards organizations such as 3GPP and 3GPP2 have successively launched IMS architectures. The purpose is to implement a variety of multimedia service applications using a standardized open architecture in mobile networks, providing more to the UE. Choice and richer feelings.

In the 3GPP Release 5 (R5, Release) phase, IMS is introduced, which is superimposed on the packet domain network, by Call Control Function (CSCF), Media Gateway Control Function (MGCF), Media Resource Function (MRF) and Home Subscriber A functional entity such as a server (HSS). The CSCF can be divided into three logical entities: S-CSCF, Proxy CSCF (P-CSCF) and Query CSCF (I-CSCF). The S-CSCF is a service switching center of the IMS, performs session control, maintains session state, is responsible for managing UE information, and generates charging information. The P-CSCF is an access point for the UE to access the IMS, completes UE registration, and is responsible for service quality ( QoS) control and security management; I-CSCF negative 1⁄2" IMS domain direction' interworking, ¹ management S-CSCF allocation And selection, hiding network topology and configuration, generating billing data, etc. The MGCF controls the gateway to implement interworking between the IMS and other networks. MRF provides media resources. The HSS stores subscription data, configuration information, and the like of the UE.

In IMS, the Session Initiation Protocol (SIP) is used as the signaling control protocol for IP multimedia sessions; the HSS and I-CSCF and the Cx interface between the HSS and the S-CSCF use the Diameter protocol for information exchange.

The IMS is applied in a packet network, a wireless local area (WLAN) network, or a next generation (NGN) network defined in 3GPP2.

When the UE wants to access the IMS, it must use the public user ID to register with the IMS network side. The public user ID is used to identify the UE in the IMS network. The public user identifier can use the Uniform Resource Identifier for the Session Initiation Protocol (SIP- URI , Session Initiation Protocol Uniform Resource Indentifier ). A UE may have one or more public user identities.

The IMS network specification states that in an IMS network, the conversion of E.164 numbers to SIP-URIs from a circuit switched network is done in the S-CSCF. When the S-CSCF receives the SIP message with the request resource identifier (Request-U I ), it maps the E.164 number in the format of "tel: URI," in the Request-URI header through the preset phone number. (ENUM DNS) The translation function is converted into a SIP-URI that identifies the UE that can be routed in the IMS network. If the conversion on the S-CSCF is unsuccessful, the corresponding SIP message is likely to be routed to the circuit switched network. The circuit-switched network performs further processing and returns to the calling UE-initiated message that initiates the SIP message. Here, the pre-set database of the ENUM DNS translation function is set by the IMS network operator according to the configuration of the UE in the IMS network. The ENUM DNS translation function corresponds to a series of URIs for the E.164 number, making the internationally uniform E.164 telephone number a network address resource that can be used in the IMS network. This implementation only considers that the SIP message is initiated by the calling UE in the IMS network, and the SIP message is used to indicate that the Requested URI of the called UE is filled with an E.164 number. However, when the SIP message is initiated by the calling UE in the circuit interaction network, and the called UE is the UE in the IMS network, there is a technical problem in using this implementation method to complete a SIP session.

Currently, the SIP session process between the calling UE of the circuit switched network and the called UE in the IMS network is: First, the calling UE initiates a call in the circuit switched network, such as initiating an initial address message (IAM, initial address) Message ) message, the call carries the E.164 number identifying the called UE information; secondly, since no functional entity in the circuit switched network has the ENUM DNS translation function for E.164 number to SIP-URI conversion, the call It will be sent to the MGCF in the home IMS network where the called UE is located. When the MGCF receives the call from the circuit-switched network, it constructs a SIP INVITE message carrying the E.164 number identifying the called UE information and sends it to the I. -CSCF; again, the I-CSCF to the HSS queries the S-CSCF currently serving the called UE according to the called UE information carried in the SIP INVITE message, and routes the SIP INVITE message to the determined S-CSCF; Finally, the SIP INVITE message is further forwarded by the S-CSCF to the called UE, and the calling UE and the called UE perform a SIP session negotiation process.

Figure 1 is a flow chart of call setup signaling from a circuit-switched network to an IMS network as specified in the IMS network specification. It is assumed that the circuit-switched network is a public switched telephone network (PSTN). The specific steps are as follows:

Step 100: The PSTN sends an IAM message to the MGCF, where the message carries a relay identifier and destination information that can be called to the called UE.

Step 101: After receiving the message, the MGCF establishes a connection from the PSTN to the packet switched network through the H.248 command on the bearer plane.

Step 102: The MGCF constructs a SIP INVITE message, where the media description information is included. Subsequent routing to the S-CSCF to the S-CSCF (SS routing process).

Step 103: Through the S-S routing process, the MGCF receives an acknowledgement (Offer Response) message carrying the capability of the called UE media stream, that is, obtaining the media stream capability of the called UE on the signaling plane.

Step 104: The MGCF modifies the connection parameters by using the H.248 command and instructs the MGW to reserve resources required for the session.

Step 105: The MGCF determines the media resource required for the session, and confirms the Offer Response message in step 103, and returns a message of the local reservation (Response Conf), that is, the confirmation message of the Offer Response is sent to the peer.

Step 106: The peer returns a response message (Conf Ack), that is, a confirmation message of the Response Conf message.

Step 107: The media gateway (MGW) in the circuit switched network reserves resources.

Step 108: After the resource reservation is completed, the MGCF returns a message for successfully reserving resources (Reservation Conf) to the peer.

Step 109: The peer returns a response message (Reservation Conf) to the MGCF.

Step 110: Perform a ringing process on the peer end.

Step 111: The MGCF forwards an address completion message (ACM, Address Complete Message) to the PST network.

Step 112: After the peer end responds, the MGCF will receive the SIP 200 OK message sent by the called UE as the final response. ' '

Step 113: The MGCF forwards an answer message (ANM, Answer Message) to the PSTN. Step 114: The MGCF notifies the MGW that the transmission of the media stream can be started by using the H.248 command.

Step 115: The MGCF returns an acknowledgement message SIP ACK for the SIP 200 OK.

The SS routing process mentioned here refers to how the S-CSCF will SIP in the IMS network. The process of routing a message to the called UE, as shown in FIG. 2, FIG. 2 is a signaling diagram of the SS routing process when the call is terminated at the PSTN. The Exit Gateway Control Function (BGCF) is the interface between the S-CSCF and the PSTN network. For detailed description, refer to TS 23.228, Section 5.5.3. Each step in FIG. 2 can be connected to the steps described in FIG. 1. According to the current IMS specification, the MGCF is regarded as an S-SCSF in the IMS network, and therefore, if the calling UE that initiated the session is located For the UE in the PST network, the S-CSCF located in the home IMS network where the called UE is located in Figure 2 is considered to be the MGCF that receives the PSTN network call.

In the existing IMS specification, the MGCF is regarded as an MGCF with the same status as the S-CSCF in multiple descriptions and process descriptions. The only difference is that the MGCF does not trigger service control, and supports circuit-switched network signaling and SIP packets. The conversion between orders. However, according to the status and implementation functions of the MGCF, the MGCF should be more like a P-CSCF than an S-CSCF. This is because many S-CSCF functions cannot be implemented by the MGCF. For example, the S-CSCF needs to save the IMS. The user's subscription information is not saved on the MGCF; the S-CSCF saves the routing information addressed to the called UE, but the MGCF does not save it. Therefore, from the perspective of signaling routing, the status of MGCF and S-CSCF are different.

Since the MGCF does not store the subscription information and the routing information of the IMS user, the MGCF cannot directly route the relay identifier and the destination information carried in the IAM message according to FIG. 1 from the PSTN to the BGCF or the P-CSCF in the IMS network. Thereby routing to the called UE to establish a call.

In order to establish a call, the MGCF must first route to the I-CSCF, and the I-CSCF queries the HSS that pre-stores the subscription information of the IMS network user, so as to reach the routing information of the called UE with the relay identifier and the destination information, and then Routed to the called UE, but because the MGCF cannot trigger service control and cannot be routed to the I-CSCF, it cannot be implemented in this way.

Further, due to call signaling sent from the circuit switched network, such as IAM carrying Can only be used to indicate the relay identification and destination information identified in the circuit switched network.

E.164 number, not the SIP-URI that can be identified in the IMS network to identify the destination information. Therefore, even if the MGCF can route the I-CSCF, it cannot query the routing information of the called UE according to the E.164 number. Thus, the call setup process from the circuit switched network to the IMS network fails.

It can be seen from the above analysis that there is a misunderstanding in locating the MGCF. When the call from the circuit-switched network is routed in the IMS network, the following problems exist, resulting in the current routing process being impossible to implement, and Business processing also has an impact.

1. Since the MGCF does not store the subscription information of the IMS network user, it cannot decide to route the call from the circuit switched network to the BGCF or the P-CSCF as the S-CSCF, and further routes to the called UE.

2. Since the MGCF cannot be routed to the I-CSCF to query the subscription information of the called UE, it is further impossible to query the routing information of the called UE according to the E.164 number used to indicate the relay identifier and the destination information, so that it is impossible to know. Which S-CSCF is currently serving the called UE, and therefore cannot directly address the S-CSCF serving the called UE, thereby making it impossible for the S-CSCF to perform subsequent procedures.

3. It is assumed that the MGCF can route the call from the circuit switched network to the BGCF or the P-CSCF for further processing to the called UE. However, this will omit the service control procedure of the S-CSCF serving the called UE. The S-CSCF, as a service node in the IMS network, cannot be omitted. Otherwise, it will cause problems in billing and security.

In summary, the establishment of call routing from the circuit switched network to the IMS network is currently not possible. Summary of the invention

In view of this, the main object of the present invention is to provide a method for establishing a call routing network to an IMS network call route, which can implement a circuit switched network to an IMS network call. The establishment of a route.

The invention also provides a system for establishing a call routing network to an IMS network call route, which system can realize the establishment of a call routing network to an IMS network call route.

The present invention also provides a number translation entity that can convert an E.164 number into a SIP-URI, thereby enabling the establishment of a circuit switched network to IMS network call routing.

According to the above object, the technical solution of the present invention is achieved as follows:

A circuit switching network to an Internet Protocol Multimedia Subsystem IMS network call routing establishment method, setting a telephone uniform resource identifier tel-URI formed by an E.164 number of a user equipment UE in a home subscription subscriber server HSS of the IMS network and the Corresponding relationship of the UE's uniform resource identifier SIP-URI for the session initiation protocol, the method further includes:

A. The media gateway control function MGCF receives a call originating from the E.164 number of the called UE initiated by the calling UE in the circuit switched network, and constructs a session initiation of the tel-URI consisting of the E.164 number of the called UE. The protocol SIP message is sent to the inquiry call control function I-CSCF;

B. The I-CSCF queries the correspondence between the HSS settings, and obtains the SIP-URI corresponding to the tel-URI formed by the E.164 number of the called UE in the SIP message, and obtains the routing information of the called UE according to the SIP-URI, and the SIP is obtained. The message is forwarded to the called UE, and the called UE and the calling UE perform a SIP session negotiation process to complete the current call.

The process of setting the correspondence relationship is as follows: The tel-URI and the SIP-URI formed by the E.164 number are saved as different public user identifiers of the same UE in the IMS network.

The tel-URI formed by the E.164 number is saved in the format of "tel: URI", wherein the URI part is the E.164 number.

The SIP message process of constructing the tel-URI consisting of the E.164 number of the called UE is as follows: The E.164 number of the called UE is filled into the constructed SIP message in the format of "tel:URT". Request-URI field. The correspondence between the I-CSCF and the HSS set in step B is queried by using the Cx interface message of the tel-URI formed by the E.164 number of the called UE.

The manner in which the Cx interface message carries the E.164 number of the called UE is as follows: The E.164 number of the called UE is filled in the public user identification field in the Cx interface message in the "tel:URT format".

When there is more than one HSS in the IMS network, the correspondence between the tel-URI and the HSS of the E.16'4 number of the same UE is set in the subscription location server SLF that administers the HSS. Before the step B, the method further includes:

The I-CSCF determines whether the tel-URI formed by the E.164 number of the called UE carried in the SIP message has a corresponding HSS. If yes, the HSS of the stored called UE subscription information is obtained, and the subsequent process of step B is performed; otherwise, The response message of the current call error is constructed by the MGCF and sent to the calling UE in the circuit switched network.

Before determining the SIP-URI corresponding to the tel-URI formed by the E.164 number of the called UE in the SIP message, the method further includes:

The I-CSCF determines whether the tel-URI formed by the E.164 number of the called UE carried in the SIP message has a corresponding SIP-URI, and if so, determines the SIP-URI corresponding to the E.164 number of the called UE carried in the SIP message. After that, perform the subsequent process, otherwise, 3⁄4 over]^0 ? A response message constructing the call error is sent to the calling UE in the circuit switched network.

The process of transmitting the SIP message to be constructed to the called UE according to step B is:

The I-CSCF queries the routing information of the UE stored in the HSS according to the SIP-URI, obtains the routing information of the called UE with the SIP-URI, determines the S-CSCF that serves the called UE, and learns the S-CSCF of the called S-CSCF. Routing, sending the constructed SIP message to the S-CSCF;

The S-CSCF sends the SIP message to the I-CSCF according to the routing information corresponding to the called UE, and the SIP message is sent to the I-CSCF. The I-CSCF address is set in advance in the MGCF, and the MGCF sends the SIP message to the I-CSCF corresponding to the address according to the set I-CSCF address;

Alternatively, an I-CSCF list is set in advance in the MGCF, and the MGCF selects an I-CSCF from the I-CSCF list according to the set rule, and sends a SIP message to the selected I-CSCF.

The corresponding relationship is a correspondence between a telephone uniform resource identifier tel-URI formed by an E.164 number of the UE and a plurality of SIP-URIs of the UE.

Setting routing information in the MGCF, the method further includes:

The MGCF receives the call signaling sent by the calling UE in the circuit-switched network, converts the call signaling into a SIP message, and sends the converted SIP message to the called UE according to the routing information set by the MGCF.

The routing information is set corresponding to the session identifier;

The MGCF also sets a correspondence between the session identifier and the connection information carried by the call signaling from the circuit switched network;

The call signaling from the circuit-switched network carries the connection information of the circuit-switched link; the process of transmitting the converted SIP message to the called UE according to the set routing information is: The MGCF determines the call according to the set correspondence relationship The connection information carried by the signaling corresponds to a session identifier, and the routing information is determined according to the session identifier.

The routing information is routing information from the MGCF to the called UE via the serving call control function S-CSCF serving the called UE.

The process of setting routing information in the MGCF is:

Setting a correspondence between a telephone uniform resource identifier tel-URI formed by an E.164 number of the UE and a uniform resource identifier SIP-URI for the session initiation protocol of the UE in the HSS of the IMS network;

The MGCF in the home IMS network of the called UE receives the caller from the circuit switched network After the UE initiates the call signaling of the E.164 number of the called UE, the session initiation protocol SIP message carrying the tel-URI of the E.164 number of the called UE is sent to the inquiry call control function I-CSCF;

The I-CSCF queries the correspondence between the HSS settings, and obtains the SIP-URI corresponding to the tel-URI formed by the E.164 number of the called UE in the SIP message, and obtains the routing information of the called UE according to the routing information of the UE saved by the HSS. The routing information is carried in the response message returned to the MGCF, and the routing information is stored by the MGCF.

The process of setting routing information in the MGCF is:

The function of converting the E.164 number to the SIP-URI is set to the MGCF in the IMS network;

After the MGCF receives the call signaling from the calling UE in the circuit-switched network and carries the E.164 number indicating the called UE, the function of converting the E.164 number into the SIP-URI is carried by the call signaling. Converting the .164 number to a SIP-URI, constructing a SIP message carrying the converted SIP-URI and transmitting it to the I-CSCF;

The I-CSCF queries the routing information of the UE that is saved by the HSS, and obtains the routing information of the called UE that has the SIP-URI carried by the SIP message. The routing information is carried in the response message returned to the MGCF, and the routing information is stored by the MGCF.

Before the sending the converted SIP message to the called UE according to the routing information set by the MGCF, the method further includes:

The MGCF determines that the SIP message of the call 'signaling conversion is not a session-independent SIP message, and performs a step of transmitting the converted SIP message to the called UE according to the routing information set in the MGCF.

The MGCF determines the routing information corresponding to the SIP message that is set by the call signaling, and sends the converted SIP message to the called party according to the routing information set in the MGCF. 0

The steps of the UE.

The routing information is set corresponding to the user identifier of the called UE; the call signaling from the circuit switched network carries the user identifier of the called UE; and the converted SIP message is sent according to the set routing information. The procedure for the called UE is: The MGCF searches whether the routing information of the called UE is saved according to the user identifier of the called UE carried in the call signaling, and if yes, sends the converted SIP message to the queried according to the determined routing information. Call the UE, otherwise, send the SIP message to the called UE according to the normal processing procedure.

The user ID of the called UE is an E.164 number identifying the called UE in the circuit switched network or a URI of the called UE in the IMS network, and the URI is a SIP-URI or a Tel-URI.

Corresponding to the E.164 number used to identify the called UE in the circuit switched network and the URI used to identify the called UE in the IMS network. '

A number conversion entity, the entity comprising a function module for converting an E.164 number into a SIP-URI, the number conversion entity transmitting an E.164 number to a function module for converting an E.164 number into a SIP-URI, converting Sent after SIP-URI.

The entity is an HSS.

The function module for converting the E.164 number into the SIP-URI has a correspondence between the E.164 number and the SIP-URI.

A system for implementing call routing establishment from a circuit switched network to an IMS network, the system comprising: a circuit switched network, an MGCF, an I-CSCF, an S-CSCF, and an HSS having a functional module for converting an E.164 number to a SIP-URI , among them,

After receiving the call from the circuit-switched network carrying the E.164 number of the called UE, the MGCF constructs a SIP message carrying the tel-URI of the E.164 number of the called UE and sends it to the I-CSCF, the I-CSCF to the HSS. The function module in which the E.164 number is converted into a SIP-URI is queried, and the tel-URI corresponding to the E.164 number of the called UE carried in the SIP message is obtained. The SIP-URI obtains the routing information of the called UE according to the SIP-URI to the HSS query, and forwards the SIP message to the called UE through the S-CSCF according to the obtained routing information, and the called UE and the calling UE perform SIP session negotiation, and complete call.

The function module for converting the E.164 number into the SIP-URI in the HSS has a correspondence between the E.164 number and the SIP-URI, and is used to convert the E.164 number into a SIP-URL.

The MGCF further has a storage module that stores an I-CSCF address or an I-CSCF list, and after receiving the call from the circuit switched network, selects the call according to the I-CSCF address in the storage module or from the I-CSCF list. An I-CSCF is routed to the I-CSCF.

As can be seen from the above solution, the present invention adds the correspondence between the telephone uniform resource identifier (tel-URI) and the SIP-URI formed by the E.164 number of the same called UE in the HSS of the IMS network. Since the subscription information of the called UE with the SIP-URI is already stored in the HSS in the prior art, the subscription information includes: routing to the S-CSCF information serving the called UE and further routing to the called UE 3⁄4 information And processing the process information and the authentication information, etc., so when the MGCF of the IMS network receives the call carrying the E.164 number, constructs a SIP message carrying the tel-URI formed by the E.164 number and sends it to the I-CSCF; I-CSCF Acquiring the SIP-URI corresponding to the tel-URI formed by the E.164 number carried in the SIP message according to the pre-stored correspondence relationship of the HSS, thereby obtaining the S-CSCF serving the called UE and the route to the S-CSCF, and sending the SIP The message is sent to the S-CSCF, and the S-CSCF sends a SIP message to the called UE to complete the routing of the local call. Therefore, the method realizes the establishment of call routing from the circuit switched network to the IMS network.

Further, in order to alleviate the traffic burden of the IMS network, the present invention sets the correspondence between the routing information corresponding to the session identifier and the connection information carried by the session identifier and the call signaling in the MGCF, when the MGCF receives the circuit switching network. After the call signaling, the routing information corresponding to the connection information carried by the call signaling is obtained according to the preset routing information, so that the SIP message of the call signaling conversion is routed to the called party according to the routing information. UE.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a flow chart of call setup signaling from a circuit switched network to an IMS network as specified in the IMS network specification;

Figure 2 is a signaling diagram of the S-S routing process when the call is terminated at the PSTN;

3 is a signaling flowchart of establishing a call route from a circuit switched network to an IMS network by an I-CSCF according to the present invention;

4 is a flow chart of a method for establishing call routing from a circuit switched network to an IMS network according to the present invention;

5 is a flow chart of a method for implementing a call process from a circuit switched network to an IMS network according to the present invention;

6 is a signaling flowchart of the present invention for transmitting call setup signaling from a circuit switched network to an IMS network;

7 is a signaling flowchart of the present invention for transmitting call release signaling from a circuit switched network to an IMS network;

8 is a flow chart of call signaling for session-independent transmission of a converted SIP message from a circuit-switched network to an IMS network according to the present invention;

9 is a flow chart of a method for transmitting call signaling from a circuit switched network to an IMS network according to the present invention;

Figure 10 is a schematic diagram of a number conversion entity. Mode for carrying out the invention

The present invention will be further described in detail below with reference to the accompanying drawings. In order to implement the present invention, the MGCF must first route the call from the circuit switched network to the I-CSCF, so that the I-CSCF queries the HSS to obtain the subscription information and routing information of the called UE, and the IC SCF will come from the circuit switched network according to the routing information. The call is routed to the S-CSCF that serves the called party, and is further routed to the called UE. For the call routing process from the S-CSCF serving the called UE to the network where the called UE is located, refer to the process described in FIG. 2. For the call routing process from the network where the called UE is located to the called UE, refer to TS 23.228. Correspond to the description of the chapter. : ·· :

The present invention can pre-set the address of the I-CSCF at the MGCF, and wait until there is a call from the circuit switched network to first route to the I-CSCF having the pre-set I-CSCF address. The present invention may also not set the I-CSCF address in the MGCF, but set an I-CSCF list. After the MGCF waits for a call from the circuit switched network, select one from the I-CSCF list according to the set rule. The I-CSCF sends the SIP message converted by the call to the selected I-CSCF.

FIG. 3 is a signaling flowchart of establishing a call route from a circuit switched network to an IMS network by an I-CSCF according to the present invention, where the specific process is:

Step 300: A call is initiated by a calling UE of the circuit switched network, and the PSTN sends an IAM message to the MGCF in the IMS network.

Step 301: The MGCF establishes a connection with the PSTN on the bearer plane by using an H.248 command.

Step 302: The MGCF constructs a SIP INVITE message, and sends the constructed message to the I-CSCF.

The I-CSCF may be an I-CSCF having an I-CSCF address preset by the MGCF, or an I-CSCF arbitrarily selected by the MGCF.

Step 303: The I-CSCF sends a location query request (Location Query) to the HSS that stores the called UE subscription information, and obtains routing information of the called UE. Step 304: The HS S returns the routing information of the called UE to the I-CSCF.

Step 305: The I-CSCF determines, according to the routing information of the called UE, the S-CSCF that is served by the called UE, further determines a route to the called UE, and sends a SIP INVITE message to the S-CSCF serving the called UE.

Step 306 ~ Step 307: The S-CSCF serving the called UE performs service control on the called UE and forwards the SIP INVITE message to the called UE according to the route to the called UE through the next hop function entity.

According to the prior art, the functional entity of the next hop of the S-CSCF is related to the terminating network of the current call. When the current call is terminated in the IMS network, the functional entity is a P-CSCF; when the call is terminated in the PSTN network, , the functional entity is BGCF.

Steps 308-310: The called UE sends an Offer Response message to the S-CSCF, and the S-CSCF forwards the Offer Response message to the MGCF through the I-CSCF, where the message indicates the media stream capability of the called UE.

Step 311: The MGCF modifies the connection parameter by using the H.248 command and instructs the MGW to reserve the resources required for the session. '

Steps 312 ~ 314, the MGCF determines the media resources required for the session that can be provided, and the MGCF follows the route to the S-CSCF and the route to the called UE, and the I-CSCF and the S-CSCF serving the called UE will Response Conf is forwarded to the called UE through the next hop function entity.

Steps 315 ~ 317, the called UE returns a Conf Ack to the MGCF via the S-CSCF and the I-CSCF serving the called UE.

Step 318: The MGW reserves resources.

Steps 319 ~ 321 After the resource reservation is completed, the MGCF forwards the Reservation Conf to the called UE through the next hop function entity via the I-CSCF and the S-CSCF that provides the service to the called UE.

Steps 322 ~ 324, the called UE receives the S-CSCF and the I-CSCF that provide services for the called UE. A reply message (Reservation Conf) is sent to the MGCF.

Steps 325 - 327. The called UE performs a Ringing process by using the S-CSCF and the I-CSCF that provide services for the called UE.

Step 328: The MGCF forwards the ACM message to the PSTN network.

Steps 329 ~ 331, after the called UE answers, the S-CSCF and the I-CSCF that provide services for the called UE send a SIP 200 OK message to the MGCF.

Step 332: The MGCF sends an ANM message to the PSTN.

Step 333: The MGCF notifies the MGW that the transmission of the media stream can be started by using an H.248 command. Step 334 - 336. The MGCF returns an acknowledgement message SIP ACK to the SIP 200 OK via the I-CSCF and the S-CSCF serving the called UE.

In the prior art, the call from the circuit-switched network carries the E.164 number used to identify the called UE information and the relay identifier. Since the IMS network does not support the E.164 number, the E.164 number must be converted. The SIP-URI supported by the IMS network can finally query the HSS for the routing information of the called UE with the SIP-URI. Therefore, for the present invention, how to route to the I-CSCF to query the routing information of the called UE and how to convert the E.164 number carried by the call from the circuit switched network into the SIP-URI supported by the IMS network is indispensable. The following describes how to convert the E.164 number carried by the call from the circuit switched network to the SIP-URI supported by the IMS network.

The invention solves the problem that the calling UE from the circuit switched network calls the IMS network by adding the correspondence between the SIP-URI of the same UE and the tel-URI formed by the E.164 number in the IMS network on the HSS in the IMS network. When called UE, the δΐΡ message cannot be routed in the IMS network, so it cannot be routed to the S-CSCF serving the called UE and further routed to the called UE.

In an IMS network, each IMS network-signed UE has one or more public user identities, and the one or more public user identities may be in a SIP-URI or "tel: URT format. HSS For each IMS network subscription UE, all the subscription information related to the UE is saved, which is used for authentication and processing of services. For a UE of an IMS network, it may not only need to communicate with UEs of another IMS network, but also with UEs in the circuit switched network. Since the calling UE in the circuit-switched network initiates a call, only the E.164 number supported by the circuit-switched network can be used. Therefore, the UE of the IMS network needs to have an E in order to communicate with the UE of the circuit-switched network. .164 number. This E.164 number may be newly assigned by the IMS network, or it may be an E.164 number that was previously used by the UE in a circuit switched network. This E.164 number is written in the form "tel: URI", such as: tel: +86-10-82882838, which is stored in the HSS as a public user identity for the UE. Also stored in the HSS, there is also a SIP-URI used by the UE to route in the IMS network, and the tel-U I and the SIP-URI formed by the E.164 number of one UE are associated. :

4 is a flow chart of a method for establishing call routing from a circuit switched network to an IMS network according to the present invention, and the specific steps are: '' ^: ''

Step 400: The calling UE in the circuit switched network initiates a call carrying an E.164 number, and the call is used to call the called UE in the IMS network, and the E.164 number carried by the call is a number indicating the called UE.

Step 401: The call initiated by the calling UE is sent to the MGCF in the IMS network to which the called UE belongs, through the circuit switched network, where the MGCF is an interworking gateway between the circuit switched network and the IMS network to which the called UE belongs.

Step 402: After receiving the call, the MGCF in the IMS network to which the called UE belongs, constructs a SIP INVITE message according to the prior art, and the message carries a tel-URI indicating an E.164 number of the called UE.

The SIP INVITE message is constructed by: filling the E.164 number indicating the called UE into the Request-URI field of the SIP INVITE message according to the "tel:UI" format, and then constructing other fields of the SIP INVITE message. These fields are constructed in the existing IMS specification TS 23.228 It has been clearly defined, including: Setting the header of the Supported field to "lOOrel", inserting a P-Asserted-Identity header, and generating a unique IMS network charging identifier to fill the header of the P-Charging-Vector field. In the header of the P-Charging-Vector header field, parameters such as the IMS network where the MGCF is located are filled in.

Step 403: The MGCF in the IMS network to which the called UE belongs sends the constructed SIP INVITE message to the I-CSCF of the IMS network to which the called UE belongs.

Step 404: After receiving the SIP INVITE message, the I-CSCF constructs a Cx interface message.

The public user identification field in the constructed Cx interface message is "tel:URT" in the Request-URI field in the SIP INVITE message from the MGCF.

Step 405: The I-CSCF sends the Cx interface message to the HSS to query the S-CSCF that is currently serving the called UE.

Step 406: After receiving the message, the HSS obtains a SIP-URI corresponding to the tel-URI formed by the E.164 number according to the set correspondence, and obtains the pre-stored subscription information of the called UE with the SIP-URI. The S-CSCF that provides service to the called UE having the SIP-URI determines the routing information of the obtained S-CSCF serving the called UE.

Step 407: The HSS sends the obtained SIP-URI, the S-CSCF that provides the service to the called UE with the SIP-URI, and the routing information to the called UE and the subscription information of the called UE to the I-CSCF.

Step 408: The I-CSCF sends the SIP INVITE message to the obtained S-CSCF serving the called UE by using the obtained routing information.

Step 409: The S-CSCF that provides the service for the called UE receives the SIP INVITE message, determines a route to the called UE, and sends the message to the called UE.

The processing after the S-CSCF receives the SIP INVITE message is the same as the prior art.

Step 410: The calling UE and the called UE perform a SIP session negotiation process to complete the current call. The SIP INVITE provided by the present invention is merely an example. For other SIP messages, the present disclosure Ming also handled this way.

In the present invention, if the HSS cannot obtain the corresponding SIP-U I according to the tel-URI formed by the E.164 number carried in the Cx interface message sent by the I-CSCF, the circuit-switched network can be configured according to the preset setting of the IMS network. The call is returned to the calling UE of the circuit-switched network according to the error processing - a message that the call is wrong.

When there are multiple HSSs in the IMS network, the I-CSCF needs to first query the subscription locator (SLF) in the IMS network, and correspondingly, the E.164 number of the same called UE is pre-stored in the SLF. The correspondence between the tel-URI and the HSS is completed according to the tel-URI constructed by the E.164 number. The result of querying the SLF is the tel-URI corresponding to the E.164 number of the UE. The HSS of the called UE related information, and then the I-CSCF sends a Cx message to the HSS to query the S-CSCF currently serving the UE corresponding to the SIP-URI.

If the SLF cannot obtain the corresponding HSS according to the tel-URI formed by the E.164 number carried in the Dx interface message sent by the I-CSCF, the call according to the IMS network may follow the error of the call from the circuit-switched network. Processing, returning to the calling UE of the circuit-switched network - a message that this call is in error. : - The circuit switched network of the present invention may be a PSTN.

The correspondence in the present invention may be a correspondence between a telephone uniform resource identifier tel-URI composed of an E.164 number of the UE and a plurality of SIP-URIs of the UE.

The disadvantages of the prior art are solved by the method provided by the present invention: Since the present invention routes the call from the circuit switched network to the I-CSCF to query the routing information of the called UE and the E that can carry the call from the circuit switched network The .164 number is converted to a SIP-URI supported by the IMS network, so the call from the circuit-switched network can be routed to the S-CSCF serving the called UE, and further routed to the called UE, so that the called UE can be made The S-CSCF providing the service performs service control on the called UE, and completes charging and security management for the called UE. Through the method provided by the invention, the calling party of the existing circuit switched network can be solved.

When the UE and the called UE in the IMS network establish a SIP session, the problem that the called UE cannot be routed to the IMS network is completed, and the implementation and application of the IMS network are improved, so that the IMS network is more mature and can be adapted to each of the specific implementations. A network condition that improves user satisfaction with UEs. Another advantage of the present invention is that the existing IMS network is smallly modified, and no physical equipment needs to be added to the IMS network. Only the E.164 number needs to be allocated according to the needs of the UE, and the same is added to the HSS in the IMS network. The technical relationship between the E.164 number and the SIP-URI of the UE can solve the technical problem proposed by the present invention, and thus is very easy for the operator of the IMS network to implement.

Although the method provided by the above invention can realize the route establishment from the circuit switched network to the IMS network, there are still disadvantages: for each call signaling interaction in the call process from the circuit switched network to the IMS network, The above method establishes a route, that is, the query mapping relationship to the HSS obtains the SIP-URI corresponding to the tel-URI formed by the E.164 number carried by the MGCF from the call signaling of the circuit switched network, and then determines the called UE according to the SIP-URI. The routing information is routed to the called UE by the S-CSCF serving the called UE according to the routing information I-CSCF of the called UE. Therefore, even if these call signaling is signaling during a call, the transmission must go back from the MGCF to the I-CSCF to the HSS and then back to the I-CSCF, and then the I-CSCF to provide services to the called UE. The S-CSCF eventually goes to the called UE. In this way, the call signaling interaction time from the circuit-switched network to the IMS network is increased, and the service burden of the IMS network is increased.

In order to overcome the above disadvantages, the present invention can also store routing information in the MGCF in the IMS network. When the MGCF receives the call signaling sent by the calling UE in the circuit switched network, the call signaling is converted into a session initiation protocol SIP message. The converted SIP message is sent to the called UE according to the routing information set by the MGCF. In this way, the method provided by the present invention can directly send a call letter through the MGCF through the S-CSCF serving the called UE without being queried by the I-CSCF. The route is routed to the called UE, thereby reducing the call signaling interaction time from the circuit switched network to the IMS network, and reducing the service burden of the IMS network.

The present invention has two ways of storing routing information in the MGCF and performing subsequent processing according to the saved routing information. The following two methods are respectively described in detail.

The first way.

Since during the call from the circuit switched network to the IMS network, there is a high probability that multiple call signaling interactions associated with the call process will occur. The first call signaling interaction in the call process needs to be implemented by the method provided by the above invention, but the second call signaling interaction, the third call signaling interaction, and the last call signaling interaction do not need to adopt the above. The method provided by the present invention sets the routing information of the current call in the MGCF, that is, sets the routing information corresponding to the session identifier, which is obtained during the first call signaling interaction of the current call. .

Since the first call signaling of the current call from the circuit switched network, that is, the call setup signaling carries the connection information, the information is used to indicate the circuit switched link, so the MGCF assigns the session identifier to the call according to the connection information. And storing routing information of the current call corresponding to the allocated session identifier. Therefore, after the subsequent call signaling from the circuit-switched network is received by the MGCF, the session identifier may be determined according to the connection information carried in the subsequent call signaling, thereby determining the routing information corresponding to the session identifier, and directly adopting the called UE according to the determined routing information. The serving S-CSCF routes subsequent call signaling to the called UE.

The session identifier of the present invention may be the call ID (Call ID) of the call. The routing information related to the current call set in the MGCF of the present invention is routing information from the MGCF to the S-CSCF serving the called UE and further routing information to the called UE.

FIG. 5 is a flowchart of a method for implementing a call process from a circuit-switched network to an IMS network according to the present invention. A call process refers to the entire process from the establishment of a call to the maintenance of a call to the release of a call. The specific steps are as follows: Step 500: During a call, the calling UE of the circuit switched network initiates call setup signaling carrying the E.164 number of the called UE and the connection information to the called UE in the IMS network.

Step 501: After receiving the call setup signal during the current call, the MGCF in the IMS network converts the call setup signaling into a SIP message according to the prior art method.

Step 502: The MGCF in the IMS network determines whether the SIP message converted by the call setup signaling is a session-independent SIP message. If yes, go to step 503; otherwise, go to step 504.

The mapping relationship between the call signaling and the SIP message in the circuit-switched network and whether the SIP message is session-independent or session-related SIP message is pre-stored in the MGCF. Therefore, the MGCF can determine the SIP message corresponding to the call signaling in the circuit switched network according to the mapping relationship, so as to determine whether the SIP message is a session charge according to whether the SIP message is a session-independent or session-related SIP message. The closed SIP message is also a session-related SIP message.

In the prior art, a session-related SIP message refers to a request message that, after receiving a corresponding response message, establishes a session, and retains the session state on each state node through which the message passes. The session can only be released after one of the User Agents (UAs) initiates a release request.

A session-independent SIP message refers to a request message that completes the request after receiving the corresponding response message, and does not retain any information on each state node through which the message passes.

Step 503: The MGCF in the IMS network sends the SIP message converted by the call setup signaling to the S-CSCF serving the called UE through the I-CSCF by using the route determined by the method provided by the foregoing method, and then is the called UE. The serving S-CSCF sends a SIP message converted by the call setup signaling to the called UE, establishes a connection between the calling UE and the called UE, and ends.

Step 504: The MGCF in the IMS network sends the SIP message converted by the call setup signaling to the called UE through the I-CSCF by using the route determined by the method provided by the foregoing method. The S-CSCF of 000500, and then the S-CSCF serving the called UE sends a SIP message converted by the call setup signaling to the called UE, and establishes a connection between the calling UE and the called UE;

And the MGCF stores the determined route of the S-CSCF serving the called UE to the called UE as the routing information of the current call, that is, the routing information of the current call is corresponding to the session identifier allocated for the call. Storage, the allocated session identifier corresponds to the connection information carried by the call setup signaling.

Step 505: The calling UE of the circuit switched network initiates call signaling carrying the connection information and the E.164 number to the called UE in the IMS network.

Step 505 and subsequent steps may also not follow step 504, but exist as a separate process.

Step 506: After receiving the call signaling, the MGCF in the IMS network converts the call signaling into a SIP message according to the method provided by the foregoing.

Step 507: The MGCF in the IMS network determines, according to the connection information carried in the call signaling, whether the routing information corresponding to the connection information is stored. If yes, go to step 509; otherwise, go to step 508.

The MGCF sets the correspondence between the connection information and the session identifier, and sets the correspondence between the session identifier and the routing information. Therefore, according to the connection information carried in the call signaling, it can be determined whether the connection information exists. Routing information.

Step 508: The MGCF in the IMS network performs the process according to steps 502 to 504.

Step 509: The MGCF in the IMS network determines, according to the routing information corresponding to the connection information, a route to the called UE through the S-CSCF serving the called UE, and passes the SIP message converted by the call signaling through the determined route. The S-CSCF serving the called UE, the S-CSCF serving the called UE sends the SIP message to: the called UE, and the called UE processes the SIP message. Step 510: The calling UE of the circuit switched network initiates release signaling carrying the connection information and the E.164 number to the called UE in the IMS network.

Step 510 and subsequent steps may also not follow step 509, but exist as a separate process.

Step 511: After receiving the release signaling, the MGCF in the IMS network converts the release signaling into a SIP message, that is, a BYE message, according to a method provided by the prior art.

Step 512: The MGCF in the IMS network performs the process according to the steps 507 to 509, so that the S-CSCF serving the called UE receives the BYB message and forwards the message to the called UE.

Step 513: The called UE removes the current call connection from the MGCF to the called UE by sending an acknowledgment message to the MGCF in the IMS network via the determined route to the S-CSCF served by the called UE.

Step 514: The MGCF in the IMS network that receives the acknowledgment message releases the session established between the MGCF and the called UE for the call, and ends.

In step 506, after receiving the call signaling, the MGCF in the IMS network may first determine whether the SIP message converted by the call setup signaling is a session-independent SIP message, and if so, directly according to the prior art method. The call setup signaling sends the called UE; otherwise, the subsequent process of step 506 is performed.

6 is a signaling flow chart of the invention for transmitting call setup signaling from a circuit-switched network to an IMS network, and the circuit-switched network is a PSTN, and the specific steps are as follows:

Step 600: A call setup is initiated by a calling UE of the PSTN, and the PST sends an IAM message to the MGCF in the IMS network.

Step 601: The MGCF establishes a connection with the PSTN on the bearer plane by using an H.248 command.

Step 602: The MGCF constructs a SIP INVITE message, and determines the route through the stored routing information of the current call, and sends the message to the S-CSCF that provides the service for the called UE. Step 603 - Step 604: The S-CSCF serving the called UE performs service control on the called UE and forwards the SIP INVITE message to the called UE according to the route to the called UE by using the next hop function entity.

Steps 605-606: The called UE sends an Offer Response message to the S-CSCF, and the S-CSCF forwards the Offer Response message to the MGCF through the I-CSCF, where the message indicates the media stream capability of the called UE.

Step 607: The MGCF modifies the connection parameter by using the H.248 command and instructs the MGW to reserve the resources required for the session.

Steps 608 ~ 610, the MGCF determines the media resources required for the session that can be provided, and the MGCF follows the route to the S-CSCF and the route to the called UE, and the I-CSCF and the S-CSCF serving the called UE will Response Conf is forwarded to the called UE through the next hop function entity.

Steps 611 ~ 613, the called UE returns a Conf Ack: to the MGCF via the S-CSCF and the I-CSCF that provide the service to the called UE.

Step 614: The MGW reserves resources.

Steps 615 ~ 617, after the resource reservation is completed, the MGCF forwards the Reservation Conf to the called UE through the next hop function by the I-CSCF and the S-CSCF providing the service to the called UE.

Steps 618 - 620. The called UE returns the Reservation Conf to the MGCF via the S-CSCF and the I-CSCF that provide services for the called UE.

Steps 621-624: The called UE performs a Ringing process by using the S-CSCF and the I-CSCF that provide services for the called UE.

Step 625: The MGCF forwards the ACM message to the PSTN network.

Steps 626-628: After the called UE answers, the S-CSCF and the I-CSCF that provide services for the called UE send a SIP 200 OK message to the MGCF.

Step 629: The MGCF sends an ANM message to the PSTN. Step 630: The MGCF notifies the MGW to start the transmission of the media stream by using an H.248 command. Steps 631 ~ 633, the MGCF returns an acknowledgement message SIP ACK to the SIP 200 OK via the I-CSCF and the S-CSCF serving the called UE.

FIG. 7 is a signaling flowchart of the present invention for transmitting call release signaling from a circuit-switched network to an IMS network, and the circuit-switched network is a PSTN, and the specific steps are as follows:

Step 700: The PSTN sends a call release signaling to the MGCF through the MGW.

Step 701: The MGCF releases the connection between the PSTN and the IMS network by using an H.248 command. Step 702: The MGCF converts the call release signaling into a BYE message, determines a route by using the stored routing information of the current call, and sends the route to the S-CSCF that provides the service for the called party.

Steps 703 to 704: After receiving the BYB message, the S-CSCF that provides the service to the called party performs service control on the called UE and forwards the message to the called UE.

Steps 705 to 706: The called UE sends a 200 OK message to the MGCF in the IMS network via the determined route by the S-CSCF serving the called UE, and the current call connection from the called UE to the MGCF is removed.

Step 707: The MGCF deletes the stored routing information of the current call, and sends a response to the call release signaling to the PSTN.

When the SIP message of the call signalling conversion from the circuit switched network is not a SIP message related to the session, such as the MESSAGE of the short message conversion, it is processed according to the method described in FIG. 8, and FIG. 8 is a circuit switching network according to the present invention. The IMS network implements a session-independent call signaling flowchart for sending the converted SIP message, and sets the circuit switching network to be a PSTN. The specific steps are as follows:

Step 800: The PSTN sends signaling carrying the short message to the MGCF through the MGW.

Steps 801 ~ 802, the MGCF converts the circuit domain short message into a SIP MESSAGE, and determines that the SIP MESSAGE is a session-independent message, so that the bearer resource is not needed, and the SIP is

MESSAGE is sent to the I-CSCF. 0 Step 803: The I-CSCF sends a Location Query to the HSS storing the information, and obtains the routing information of the called UE.

Step 804: The HSS returns the routing information of the called UE to the I-CSCF.

Step 805: The I-CSCF determines, according to the routing information of the called UE, the S-CSCF that is served by the called UE, further determines a route to the called UE, and sends a SIP MESSAGE message to the S-CSCF serving the called UE.

Step 806 - Step 807: The S-CSCF serving the called UE performs service control on the called UE and forwards the SIP MESSAGE message to the called UE according to the route to the called UE.

Steps 808-810: After the called UE answers, the S-CSCF and the I-CSCF that provide services for the called UE send a 200 OK message to the MGCF.

Step 811: The MGCF sends an acknowledgement message to the PSTN.

The second way.

In order to better implement the present invention, it is also possible to distinguish whether the SIP message converted by the call signaling from the circuit switched network is a session-independent SIP message or a session-related SIP message, as long as it is sent from the circuit switched network. The call signaling of the IMS network stores the routing information of the called UE to which the call signaling is to be sent in the MGCF of the IMS network, that is, the routing information of the called UE is stored in the storage manner of the routing information corresponding to the user identifier of the called UE. Therefore, the call signaling that is subsequently sent to the same called UE can be directly routed to the called UE according to the stored routing information of the called UE through the S-CSCF serving the called UE.

The user ID of the called UE is an E.164 number identifying the called UE in the circuit switched network or a URI identifying the called UE in the IMS network, the URI being a SIP-URI or a Tel-URL

The present invention may also associate user identities for identifying the same called UE in different networks, both establishing an E.164 number for identifying the called UE in the circuit switched network and for identifying the called UE in the IMS network. The correspondence between URIs.

Of course, in the user ID of the called UE, such as SIP-URI or E.164 number corresponding to the routing letter The information storage mode stores the routing information of the called UE, and also identifies the session identifier corresponding to the routing information, and further corresponding connection information.

9 is a flow chart of a method for transmitting call signaling from a circuit switched network to an IMS network according to the present invention, and the specific steps are as follows:

Step 900: During a call, the calling UE of the circuit switched network initiates call signaling carrying the E.164 number of the called UE to the called UE in the IMS network.

Step 901: After receiving the call signaling in the current call, the MGCF in the IMS network converts the call signaling into a SIP message according to a method in the prior art.

Step 902: The MGCF in the IMS network stores, according to the prior art, the route of the S-CSCF serving the called UE to the called UE as the routing information of the called UE, that is, as having a user identifier, such as SIP. The routing information of the called UE of the URI or E.164 number is stored.

Step 903: The MGCF in the IMS network transmits the SIP message converted by the call signaling to the called UE through the I-CSCF by using the S-CSCF serving the called UE to the called UE according to the prior art. The serving S-CSCF then sends the SIP message converted by the call signaling to the called UE for processing by the S-CSCF serving the called UE.

Step 904: The calling UE of the circuit switched network again initiates call signaling carrying the E.164 number of the called UE to the called UE in the IMS network.

Step 904 and subsequent steps may also not follow step 903, but exist as a separate process.

Step 905: After receiving the call signaling, the MGCF in the IMS network converts the call signaling into a SIP message according to a method provided by the prior art.

Step 906: The MGCF in the IMS network determines, according to the E.164 number of the called UE carried in the call #order, whether the routing information corresponding to the called UE is stored. If yes, step 908 is performed; otherwise, step 907 is performed. In the present invention, the MGCF may also determine, according to the user identifier carried by the call signaling, such as a SIP-URI, whether to store routing information corresponding to the called UE having the user identifier, and if yes, perform step 908; otherwise, perform steps 907.

Step 907: The MGCF in the IMS network performs the process according to the procedure according to step 901 to step 903.

Step 908: The MGCF in the IMS network determines, according to the routing information corresponding to the called UE, a route through the S-CSCF serving the called UE to the called UE, and passes the SIP message converted by the call signaling through the determined route. It is sent to the S-CSCF serving the called UE, and the S-CSCF serving the called UE sends the SIP message to the called UE for processing accordingly.

The session-independent SIP message according to the present invention may be a SIP MESSAGE message obtained by converting a short message point-to-point protocol (SMPP) message of a circuit switched network, or may be a SIP OPTION message and a SIP INFO message.

Since the present invention pre-sets the correspondence between the routing information corresponding to the session identifier and the connection information carried by the session identifier and the call signaling in the MGCF, when the MGCF receives the call signaling from the circuit-switched network, according to the preset route. The information acquires routing information corresponding to the connection information carried by the call signaling, so as to be routed to the S-CSCF serving the called UE according to the routing information, and further routed to the called UE. Therefore, the present invention can transmit call signaling from the circuit switched network to the IMS network, and the SIP message converted by the call signaling is a session related message, and can be directly used by the MGCF as the called UE without being queried by the I-CSCF. The serving S-CSCF is routed to the called UE, thereby reducing the call signaling interaction time from the circuit switched network to the IMS network, and reducing the service burden of the IMS network.

Further, when the MGCF stores the routing information, the MGCF may also store the routing information corresponding to the user identifier of the called UE, so that when the MGCF receives the call signaling from the circuit switched network, the MGCF may also The set routing information obtains the routing information corresponding to the user identifier carried in the call signaling, so that the call signaling is used according to the routing information. The S-CSCF serving the called UE is routed to the called UE. Therefore, the present invention can transmit call signaling from the circuit switched network to the IMS network, and the SIP message converted by the call signaling can be a session-independent message or a session-related message, and can also be queried without the I-CSCF. The S-CSCF serving the called UE is directly routed to the called UE by the MGCF, thereby reducing the call signaling interaction time from the circuit switched network to the IMS network, and reducing the service burden of the IMS network.

In order to implement the conversion from the E.164 number to the SIP-URI, the present invention also provides a number conversion entity, which may be an HSS, and FIG. 10 is a schematic diagram of a number conversion entity. As shown in the figure, the number conversion entity has The E.164 number is converted into a SIP-URI function module. When the number conversion entity receives the E.164 number, it sends the E.164 number to the function module that converts the E.164 number to the SIP-URI, and converts it to SIP. - URI is forwarded out.

The function module for converting the E.164 number into the SIP-URI in the number conversion entity has a correspondence between the E.164 number and the SIP-URI, and the function module performs number conversion according to the corresponding relationship. '

Of course, in order to realize the establishment of the call routing of the circuit switched network to the IMS network, the present invention also resets the IMS network in the prior art, that is, the E.164 number is converted into the SIP in the HSS of the IMS network. The function module of the URI, when the MGCF of the IMS network receives the call from the E.164 number of the called UE initiated by the calling UE in the circuit switched network, constructs a tel-URI consisting of the E.164 number carrying the called UE. The SIP message is sent to the I-CSCF of the IMS network, and the function module of the I-CSCF to the HSS that converts the E.164 number into the SIP-URI is queried, and the tel composed of the E.164 number of the called UE carried by the SIP message is obtained. The SIP-URI corresponding to the URI obtains the routing information of the called UE according to the SIP-URI according to the prior art to the HSS query, and forwards the SIP message to the called UE, and the called UE and the calling UE perform the SIP session negotiation process. This call.

In the present invention, a functional module in the HSS that converts an E.164 number into a SIP-URI has Correspondence between the E.164 number and the SIP-URI, the function module performs number conversion according to the corresponding relationship.

In the present invention, in order to enable the MGCF of the IMS network to route the call to the I-CSCF, a storage module storing the I-CSCF address or the I-CSCF list may also be added in the MGCF, after the MGCF receives the call of the circuit-switched network. The call can be routed to the determined I-CSCF according to the I-CSCF address stored by the own storage module or by selecting an I-CSCF from the stored I-CSCF list.

The above description is only the preferred embodiment of the present invention and is not intended to limit the scope of the present invention.

Claims

Claim

A method for establishing a circuit switching network to an internet protocol multimedia subsystem IMS network call route, characterized in that a telephone uniform resource identifier formed by an E.164 number of a user equipment UE is set in a home subscriber server HSS of the IMS network. Corresponding relationship between the tel-URI and the uniform resource identifier SIP-URI of the UE for the session initiation protocol, the method further includes:

The method according to claim 1, wherein the process of setting the correspondence relationship is: performing both the tel-URI and the SIP-URI formed by the E.164 number as different public user identifiers of the same UE in the IMS network. save.

3. The method according to claim 2, wherein the tel-URI formed by the E.164 number is saved in a format of "tel:URT", wherein the URI part is the E.164 Number.

4. The method according to claim 1, wherein the SIP message process of constructing the tel-URI formed by the E.164 number of the called UE is: the E.164 number of the called UE is "tel:URT, the format is populated into the Request-U I field in the constructed SIP message.

The method according to claim 1, wherein the correspondence between the I-CSCF and the HSS set in step B is a Cx interface message of the tel-U I formed by the E.164 number carrying the called UE. Queryed.

The method according to claim 5, wherein the Cx interface message carries the E.164 number of the called UE in the following manner: The E.164 number of the called UE is filled in the "tel:UT format" The public user ID field in the Cx interface message.

7. The method according to claim 1, wherein when there is more than one HSS in the IMS network, the tel-URI and the HSS formed by the E.164 number of the same UE are set in the subscription location server SLF that administers the HSS. Corresponding relationship, before step B, the method further includes:

The method of claim 1, wherein before the determining, in the step B, the SIP-URI corresponding to the tel-URI formed by the E.164 number of the called UE, the method further includes:

The I-CSCF determines whether the tel-URI formed by the E.164 number of the called UE carried in the SIP message has a corresponding SIP-URI, and if so, determines the SIP-URI corresponding to the E.164 number of the called UE carried in the SIP message. After that, the subsequent process is performed. Otherwise, the response message that the call error is constructed by the MGCF is sent to the calling UE in the circuit switched network.

The method according to claim 1, wherein the process of transmitting the constructed SIP message to the called UE according to step B is:

The I-CSCF queries the routing information of the UE stored in the HSS according to the SIP-URI, obtains the routing information of the called UE with the SIP-URI, and determines the S-CSCF that provides the service to the called UE. Obtaining the route of the S-CSCF, and sending the constructed SIP message to the S-CSCF; the S-CSCF sends the SIP message to the called party according to the routing information corresponding to the called UE.

10. The method according to claim 1, wherein the process of sending the SIP message to the I-CSCF in step A is:

The I-CSCF address is set in advance in the MGCF, and the MGCF sends the SIP message to the I-CSCF corresponding to the address according to the set I-CSCF address;

The method according to claim 1, wherein the correspondence relationship is a correspondence between a telephone uniform resource identifier tel-URI formed by an E.164 number of the UE and a plurality of SIP-URIs of the UE.

The method of claim 1, wherein the routing information is set in the MGCF, the method further comprising:

The method according to claim 12, wherein the routing information is set corresponding to the session identifier;

The call signaling from the circuit-switched network carries the connection information of the circuit-switched link; the process of transmitting the converted SIP message to the called UE according to the set routing information is: The MGCF determines the call according to the set correspondence relationship The connection information carried by the signaling corresponds to There is a session identifier, and routing information is determined according to the session identifier.

The method according to claim 12, wherein the routing information is routing information from the MGCF to the called UE via the serving call control function S-CSCF serving the called UE.

The method according to claim 12, wherein the process of setting routing information in the MGCF is:

Setting, in the HSS of the IMS network, a correspondence between the telephone uniform resource identifier tel-U I formed by the UE's E.164 number and the UE's uniform resource identifier SIP-URI for the session initiation protocol;

The MGCF in the IMS network of the called UE receives the caller from the circuit switched network.

After the UE initiates the call signaling of the E.164 number of the called UE, the session initiation protocol SIP message carrying the tel-URI of the E.164 number of the called UE is sent to the inquiry call control function I-CSCF;

The I-CSCF queries the correspondence between the HSS settings, and obtains the SIP-URI corresponding to the td-URI formed by the E.164 number of the called UE in the SIP message, and obtains the routing information of the called UE according to the routing information of the UE saved by the HSS. The routing information is carried in the response message returned to the MGCF, and the routing information is stored by the MGCF.

16. The method according to claim 12, wherein the process of setting routing information in the MGCF is:

The I-CSCF queries the routing information of the UE saved by the HSS, and is carried by the SIP message. The routing information of the called UE of the SIP-URI carries the routing information in the response message returned to the MGCF, and the routing information is stored by the MGCF.

The method according to claim 12, wherein before the sending the converted SIP message to the called UE according to the routing information set by the MGCF, the method further includes:

The MGCF determines that the SIP message converted by the call signaling is not a session-independent SIP message, and performs a step of transmitting the converted SIP message to the called UE according to the routing information set in the MGCF.

The method of claim 12, wherein before the sending the converted SIP message to the called UE according to the routing information set by the MGCF, the method further includes:

The MGCF determines the routing information corresponding to the SIP message to which the call signaling is set, and performs the step of transmitting the converted SIP message to the called UE according to the routing information set in the MGCF.

The method according to claim 12, wherein the routing information is set corresponding to a user identifier of the called UE;

The call signaling from the circuit-switched network carries the user identifier of the called UE; the process of transmitting the converted SIP message to the called UE according to the set routing information is: the called UE carried by the MGCF according to the call signaling The user identifier is used to search whether the routing information of the called UE is saved. If yes, the converted SIP message is sent to the called UE according to the determined routing information. Otherwise, the SIP message is sent to the called UE according to the normal processing procedure.

20. The method according to claim 19, wherein the user identifier of the called UE is an E.164 number identifying the called UE in the circuit switched network or a URI of the called UE in the IMS network, the URI Is a SIP-URI or a Tel-URI.

21. The method of claim 20, wherein the E.164 number used to identify the called UE in the circuit switched network and to identify the called UE in the IMS network The URI corresponds.

22. A number conversion entity, characterized in that the entity comprises a functional module for converting an E.164 number into a SIP-URI, the number conversion entity transmitting the received E.164 number to converting the E.164 number to SIP- The function module of the URI is sent after being converted to a SIP-URI.

23. The entity of claim 22, wherein the entity is an HSS.

The entity according to claim 22, wherein the function module for converting the E.164 number into the SIP-URI has a correspondence between the E.164 number and the SIP-URI.

25. A system for establishing call routing establishment from a circuit switched network to an IMS network, the system comprising: a circuit switched network, an MGCF, an I-CSCF, an S-CSCF, and having an E.164 number converted to a SIP- URI's functional module HSS, where

After receiving the call from the circuit-switched network carrying the E.164 number of the called UE, the MGCF constructs a SIP message carrying the tel-URI of the E.164 number of the called UE and sends it to the I-CSCF, the I-CSCF to the HSS. In the function module query for converting the E.164 number into the SIP-URI, the SIP-URI corresponding to the tel-URI formed by the E.164 number of the called UE carried in the SIP message is obtained, and the SIP-URI is obtained according to the SIP-URI query. The routing information of the UE is forwarded to the called UE through the S-CSCF according to the obtained routing information, and the called UE and the calling UE perform SIP session negotiation to complete the call.

26. The system according to claim 25, wherein 'the function module for converting the E.164 number to the SIP-URI in the HSS has a correspondence between the E.164 number and the SIP-URI, and is used for Convert E.164 number to SIP-URL

27. The system according to claim 25, wherein the MGCF further has a storage module that stores an I-CSCF address or an I-CSCF list, and is configured to store the call according to the call after receiving the call from the circuit switched network. The I-CSCF address in the module or an I-CSCF route from the I-CSCF list is routed to the I-CSCF.