CN102595372B - User's loaming method and ICS enhancing networks - Google Patents

Abstract

The invention discloses a kind of user's loaming methods, and BPF is added in ICS enhances network；The described method includes：After BPF receives the roaming number request message of circuit-switched CS domain, routing number is provided, the call routing in the CS domains to BPF；BPF routes the call to local call application server L TAS, and the L TAS trigger CS Service controls, and serve as user agent after Service control success, and session is established to called subscriber.The present invention discloses a kind of ICS to enhance network.The present invention realizes the communication service for by the UE of the non-ICS enhancings network of ICS enhancing network insertions, realizing the UE to non-ICS enhancing networks, and then realizes compatibility of the ICS enhancing networks to the UE of non-ICS enhancing networks, and the business in CS domains can be also realized based on IMS.

Description

User roaming method and ICS enhanced network

Technical Field

The present invention relates to a roaming technology in an IP Multimedia Subsystem (IMS) network architecture, and in particular, to an IMS Centralized Service (ICS) based user roaming method and an ICS enhanced network.

Background

An Internet Protocol (IP) Multimedia Subsystem (IMS) is an IP-based network architecture proposed by the third Generation partnership project (3 GPP), which constructs an open and flexible service environment, supports Multimedia applications, and provides rich Multimedia services to users.

The IMS is not related to an access technology, and may provide services for Packet Switching (PS) access networks such as General Packet Radio Service (GPRS), Wireless Local Area Network (WLAN), and the like, and may also provide services for mobile cellular networks such as Global System for mobile communications (GSM), Universal Mobile Telecommunications System (UMTS), and the like.

Mobile networks such as GSM and UMTS use Circuit-Switched technology, called Circuit Switched (CS) domain, to provide basic voice services and supplementary services based on voice services for users. When the CS domain accesses the IMS, it evolves to an access mode, and the services are provided by the IMS in a unified manner, and this technology is called IMS Centralized Service (ICS).

Fig. 1 is an architecture diagram of an IMS centralized control service, as shown in fig. 1, including: user Equipment (UE) 101, Universal mobile telecommunications System Radio Access Network (UTRAN, Universal mobile telecommunications System Radio Access Network)/GSM EDGE Radio Access Network (GERAN, GSM EDGE Radio Access Network)102, ICS mobile switching Center Server (ICS MSC Server, mobile switching Center Server)103, circuit domain Media Gateway (CS-MGW, CS Media Gateway)104, Home Subscriber Server (HSS, Home Subscriber Server)105, Call session control Function (CSCF, Call session control Function)106, and Telephony Application Server (TAS, telephone Application Server) 107; wherein,

UTRAN/GERAN 102, is used for taking charge of the radio resource access control and management;

the ICS MSC Server 103, in addition to completing the access, mobility management, and call control functions of the CS user equipment, also serves as a Session Initiation Protocol (SIP) user agent, and implements the conversion between the CS signaling and the SIP message, instead of accessing the user to the IMS.

CS-MGW 104 for providing media resources and managing and controlling the media resources;

HSS 105 is used to store subscription data for subscribers and provide support for calls or sessions.

The CSCF 106 is further divided into an Interrogating CSCF (I-CSCF) and a Serving CSCF (S-CSCF). The I-CSCF interacts with the HSS to request the HSS to allocate the S-CSCF to the user or inquire the S-CSCF where the user is located; the S-CSCF provides functions for registration, call control, etc. for the user.

TAS 107, responsible for handling traditional CS domain telephony traffic.

UE 101 is accessed to ICS MSC Server 103 through CS control signaling, ICS MSC Server acts as user agent, replaces CS user equipment 101 to access CSCF 104 of IMS network, and establishes session connection with remote user, and ICSMSC Server 103 controls CS-MGW 104 to complete the conversion between the media stream on CS bearing and the media stream on IP bearing, and establishes the media connection between user equipment 101 and remote user.

From the perspective of network development, it is accepted by the industry that the core network is finally developed to be uniformly managed by IMS, and 3GPP has established ICS technology in release 8, and enhanced access of the CS network to the IMS network through an MSC Server, which is a key technology for the evolution of the CS network to the IMS network. However, the existing ICS technology does not consider reducing the cost of the ICS MSC, and the existing standard only enhances based on the traditional Mobile Switching Center (MSC) to support the ICS service triggering, and actually, if the service is uniformly migrated to the IMS network, the ICS MSC can be simplified to reduce the cost of the core network.

Therefore, an ICS enhanced network architecture is proposed in the industry to weaken the function of the MSC Server, and compared with the traditional ICS, the CS network is completely sunk to an access layer, so that the network structure is simpler and does not depend on the CS Core and a No. seven signaling network.

Fig. 2 is a schematic diagram of an ICS enhanced network architecture, as shown in fig. 2, and on the basis of the structure shown in fig. 1, the following new network elements are included:

the difference between the Mobile Access gateway Control Function (mAGCF) 203, mAGCF203 and ICS MSC Server 104 lies in that mAGCF mainly provides signaling conversion between CS and SIP, and does not have the Access management and service Control Function of the traditional CS domain MSC Server to the user any more, and also cancels the interface with the traditional CS network, and the interworking between mAGCF203 and the traditional CS network is realized by the Media gateway Control Function (MGCF, Media Gate Control Function) of the IMS network.

Fig. 3 is a flowchart of the registration of the ICS enhanced service, and as shown in fig. 3, the UE accesses to the IMS network through the mAGCF and initiates registration in the IMS network. For simplicity, the flow in fig. 3 focuses on the location update procedure and the IMS registration procedure of the CS domain, and omits the security authentication procedure therein.

The ICS enhanced registration procedure comprises the following steps:

step 301-step 302, the UE initiates a CS attach procedure in the CS access network, and sends a CS location update request to the ICS MSC Server, where the message carries an International Mobile Subscriber Identity (IMSI) of the UE;

step 303, the ICS MSC Server converts the received location update request message into an SIP registration message, obtains the user home domain name according to the identity IMSI, and sends a registration message to the UE home domain IMS network entry network element I-CSCF, where the registration message carries a Private user identity (PVI, Private user identity) derived by the ICS MSC Server according to the IMSI of the UE.

Step 304, the I-CSCF receives the registration message, and inquires the registration state from the HSS, wherein the message carries the PVI of the UE. The HSS searches the current UE registration state according to the PVI of the UE, if the UE is re-registered, the HSS returns the S-CSCF address registered by the UE, and if the UE is registered for the first time, the HSS selects one S-CSCF address or returns one S-CSCF capability list;

step 305, if the HSS returns the S-CSCF address information, the I-CSCF forwards the registration request message to the S-CSCF, if the HSS returns the S-CSCF capability list, the I-CSCF selects an S-CSCF with the capability meeting the requirement and forwards the registration request message to the S-CSCF;

step 306, the S-CSCF receives the registration request message and may trigger the authentication procedure, which is not described herein too much for the sake of simplicity;

step 307, the S-CSCF acquires user service subscription data from the HSS;

step 308, the S-CSCF returns a registration success message to the mAGCF, where the message carries a Public User Identity (PUI) list available for the UE and a default PUI;

step 309, the mAGCF stores the S-CFCF address and the user identification list and default PUI, and returns a location update success message to the UE;

in the ICS enhancement technology, the MSC function is weakened, no longer has a service processing function, and is only responsible for protocol conversion and resource management work, and service triggering and control are both centralized to the home IMS core network, whereas for the conventional CS network roaming mechanism, service control and triggering are handled by the visited MSC, so that according to the existing ICS enhancement technology, when the conventional user roams to the network described in the background technology, service cannot be triggered.

Disclosure of Invention

In view of this, the present invention mainly aims to provide a user roaming method and an ICS enhanced network, which can implement compatibility of the ICS enhanced network with communication services of other mobile network users.

In order to achieve the purpose, the technical scheme of the invention is realized as follows:

a user roaming method, add the network element of marginal agency function (BPF, Bounds ProxyFunction) in ICS enhanced network; the method comprises the following steps:

after receiving a roaming number request message of a Circuit Switching (CS) domain, the BPF provides a routing number, and a call of the CS domain is routed to the BPF;

the BPF routes the call to a Local telephone application Server (L-TAS), which triggers the traditional CS service control and acts as a user agent after the service control is successful, establishing a session to the called user.

Preferably, the BPF provides a routing number, and the routing of the call in the CS domain to the BPF specifically includes:

after receiving a roaming number request message sent by a Home Location Register (HLR) to which the user belongs, the BPF determines a routing number pointing to the BPF or the L-TAS and sends the routing number to the HLR;

the HLR informs the user of the CS domain, and the user routes the call to the BPF through the routing number.

Preferably, before the BPF sends the routing number to the HLR, the method further includes:

the BPF checks whether the called user is registered in the BPF, and rejects the call when the called user is not registered; associating the registration information of the user during registration; the registration information includes the mAGCF address information of the mobile access gateway control function entity and the Local Initial filter control (L-iFC) information bound during the user registration.

Preferably, the BPF provides a routing number specifically as:

and the BPF sends a roaming number request message to the L-TAS, and the L-TAS allocates a routing number pointing to the BPF and returns the routing number to the BPF.

Preferably, before the L-TAS assigns the routing number, the method further includes:

and the L-TAS judges whether the CS subscription data of the called user exists or not, if not, the CS subscription data is acquired through the HLR to which the called user belongs, and the call is rejected when the acquisition fails or the CS subscription data of the called user cannot be acquired.

Preferably, the method further comprises:

and the BPF sets the AS address in the L-iFC generated when the called user registers AS the target L-TAS.

Preferably, before the BPF sends the routing number to the HLR, the method further includes:

and the BPF stores the corresponding relation between the called user number and the routing number in the roaming number request message.

Preferably, the routing number is composed of an address number and a group of random numbers, wherein the address number is used for call routing, and the random numbers are used for storing called subscriber numbers in an associated manner.

Preferably, the BPF routing the call to the L-TAS is specifically:

after receiving a call establishment request message or a session request invitation message, the BPF associates the number of the original called user according to the routing number in the message, and when the association is successful, the number of the original called user is replaced by an associated number, and the L-iFC is triggered to route the call to the L-TAS; and when the association fails, judging whether the routing number is distributed for the BPF, and if so, rejecting the call.

Preferably, the BPF routing the call to the L-TAS is specifically:

and the L-TAS receives the session invitation message, finds out the called user number stored when the L-TAS distributes the routing number through the routing number in the message, and performs service control on the call according to the CS subscription data signed by the called user and associated with the called user number.

Preferably, the traffic control comprises at least one of:

the L-TAS triggers a supplementary service according to the user subscription data;

the L-TAS triggers a call restriction service according to an operation strategy of an operator;

and the L-TAS judges the call authority of the user according to the user subscription data.

An ICS-enhanced network comprising a mAGCF, a BPF, and an L-TAS; wherein,

the BPF is used for providing a routing number after receiving a roaming number request message of a CS domain, and the call of the CS domain is routed to the BPF;

a BPF for routing calls to the L-TAS;

and the L-TAS is used for triggering the traditional CS service control, and serving as a user agent after the service control is successful, and establishing a session for a called user.

Preferably, the BPF is further configured to, after receiving a roaming number request message sent by an HLR to which the subscriber belongs, determine a routing number pointing to the BPF or the BPF, and send the routing number to the HLR; the HLR informs the user of the CS domain, and the user routes the call to the BPF through the routing number.

Preferably, before sending the routing number to the HLR, the BPF is further configured to check whether the called subscriber is registered in the BPF, and reject the call if the called subscriber is not registered; associating the registration information of the user during registration; the registration information comprises mAGCF address information of a mobile access gateway control function entity and local initial filter control L-iFC information bound during user registration.

Preferably, the BPF is further configured to send a roaming number request message to the L-TAS; the L-TAS is further used for allocating a routing number pointing to the L-TAS and returning the routing number to the BPF.

Preferably, before allocating the routing number, the L-TAS further determines whether there is CS subscription data of the called subscriber, and if not, acquires the CS subscription data through the HLR to which the called subscriber belongs, and rejects the call if the acquisition fails or the CS subscription data of the called subscriber cannot be acquired.

Preferably, after receiving the call establishment request message or the session request invitation message, the BPF associates the number of the original called user further according to the routing number in the message, and when the association is successful, replaces the number of the original called user with the associated number, triggers the L-iFC, and routes the call to the L-TAS; and when the association fails, judging whether the routing number is distributed for the BPF, and if so, rejecting the call.

Preferably, after receiving the session invitation message, the L-TAS searches for the called subscriber number stored when the L-TAS allocates the routing number through the routing number in the message, and performs service control on the call according to the CS subscription data signed by the called subscriber associated with the called subscriber number.

When the non-ICS-enhanced network UE roams into the ICS-enhanced network, since the ICS-enhanced network is not compatible with the existing mobile network, for the UE roaming into the ICS-enhanced network, the UE cannot enjoy the communication service provided by the ICS-enhanced network because the UE cannot register with the ICS-enhanced network. The invention sets BPF, when mAGCF receives the call establishment request message of UE of non-ICS enhanced network, it determines the accessed BPF immediately, and sends session invitation message to the BPF; and the BPF triggers the third-party service control through the L-iFC, forwards the received session invitation message to the L-TAS, triggers the CS service control through the L-TAS, and establishes a session with an opposite terminal as an agent of the UE after the triggering is successful. Thus, the UE accessed to the non-ICS enhanced network by the ICS enhanced network is realized, and the communication service to the UE of the non-ICS enhanced network is realized. The invention realizes the compatibility of the ICS enhanced network to the UE of the non-ICS enhanced network, and can also realize the service of the CS domain based on the IMS.

Drawings

Fig. 1 is an architecture diagram of an IMS centralized control service;

FIG. 2 is a schematic diagram of an ICS-enhanced network architecture;

FIG. 3 is a flowchart of ICS enhanced service registration;

FIG. 4 is a schematic diagram of an ICS-enhanced network architecture according to the present invention;

FIG. 5 is a flowchart illustrating a conventional CS user roaming to an ICS enhanced network to initiate a call according to a first embodiment of the present invention;

fig. 6 is a flowchart illustrating a conventional CS user roaming to the ICS enhanced network for originating calls according to the second embodiment of the present invention.

Detailed Description

The basic idea of the invention is that by setting BPF, after mAGCF receives the call establishment request message of UE of non-ICS enhanced network, it immediately determines the accessed BPF and sends session invitation message to the BPF; and the BPF triggers the third-party service control through the L-iFC, forwards the received session invitation message to the L-TAS, triggers the CS service control through the L-TAS, and is used as an agent of the UE to establish the session with the opposite terminal after the triggering is successful.

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the accompanying drawings by way of examples.

Fig. 4 is a schematic diagram of an ICS-enhanced network architecture of the present invention, as shown in fig. 4, compared with the existing ICS-enhanced network, the ICS-enhanced network of the present invention adds a BPF, and in addition, the present invention also correspondingly upgrades mAGCF, I-CSCF, HSS, and L-TAS network elements in the ICS-enhanced network, so as to enhance the corresponding functions of these network elements, specifically:

the mAGCF is used for sensing whether the current UE is the other network user or not when the UE is attached, and selecting a proper BPF to send a registration request when finding that the user of the other network roams to the ICS enhanced network;

after receiving the redirection request message of the I-CSCF, the mAGCF sends a registration message according to the redirection address in the message;

the mAGCF further has a capability of acquiring a Temporary Identity (TMSI), and when the mAGCF receives a Temporary Identity user identifier carried in a location update request message, the mAGCF acquires an international Mobile Identity IMSI of the UE, where the acquisition mode includes the following modes:

a1, mAGCF is acquired to UE;

b1, mAGCF if it can recognize the TMSI, it gets to the mAGCF that allocated TMSI according to the TMSI, or gets through the MSC.

And the I-CSCF is used for sensing whether the current UE is other network users or not when receiving the registration request message, and informing the mAGCF of redirecting to the BPF or forwarding the registration request message to the BPF through the redirecting request message when finding that the UE roams to the ICS enhanced network for other network users.

And the HSS is used for returning the indication that the user is the other network user when the current UE is judged to be the other network user when the I-CSCF inquires the user registration state message is received.

And the BPF has protocol conversion capability, stores the registration information after receiving the registration request message, acquires the PVI information of the UE in the registration request message, and acquires the IMSI of the UE according to the PVI information of the UE, and sends a position updating request message to the HLR to which the UE belongs by adopting an MAP protocol, wherein the IMSI information and the BPF address information of the UE are carried in the position updating request message.

The BPF is also used for storing user data, triggering third party registration after receiving the user data insertion request message, and forwarding the acquired user signing service data to the local telephone application server L-TAS.

And before the BPF triggers the third party to register, generating a local initial filter control iFC, wherein the iFC comprises an address of the L-TAS and a service triggering standard.

The BPF also stores the registration address of the mAGCF; and providing a routing number, and after receiving a CS domain roaming number providing request message of the UE, the BPF allocates the routing number or acquires the routing number through the L-TAS.

The BPF receives the call setup request and routes the call to the L-TAS according to the L-iFC.

And the L-TAS provides a routing number, and allocates the routing number after receiving the BPF roaming number providing request message.

And the CS service control receives the session invitation message and triggers the service control according to the signed service.

Specifically, in the invention, BPF receives the request message of CS network roaming number, provides the routing number, and makes the call route to BPF; BPF routes the call to local telephone application server L-TAS, L-TAS triggers traditional CS service control, after success, L-TAS acts as user agent to set up conversation to called user. The BPF provides a routing number, specifically, the BPF receives a request message for providing a roaming number sent by an HLR to which a user belongs, the BPF provides a routing number pointing to the BPF or an L-TAS, the routing number is returned to the HLR, the HLR informs a CS network, and a call is routed to the BPF or the L-TAS through the routing number. Before the BPF returns the routing number, storing the corresponding relation between the called user number and the routing number in the request message for providing the roaming number; before the BPF returns the routing number, the BPF checks whether the called user is registered in the BPF, and if not, the call is rejected; if so, associating the registration information of the user; the registration information includes mAGCF address information bound when the user registers, local L-iFC information, and the like.

The BPF provides the routing number further comprises that the BPF sends a roaming number request message (the message can be received by the BPF and then forwarded) to the L-TAS, and the L-TAS distributes the routing number pointing to the BPF and returns the routing number to the BPF; the routing number is composed of an address number and a group of random numbers, wherein the address number is used for calling routing, and the random numbers are used for storing called subscriber numbers in an associated mode.

The BPF sends a roaming number request message to the L-TAS, and also has the function that the BPF sets an AS address in the L-iFC generated when the called user registers AS the target L-TAS. Before the L-TAS distributes the routing number, the called user number in the received message is stored, and the relationship between the called user number and the routing number is established; before the L-TAS distributes the routing number, judging whether CS subscription data of a called user exists or not, and if not, acquiring the CS subscription data from an HLR to which the called user belongs by the L-TAS; if the CS subscription data cannot be acquired or acquisition fails, the call is rejected.

The BPF routes the call to the L-TAS, specifically, the BPF receives a call establishment request message or a session request invitation message, associates the original called subscriber number according to the routing number in the message, successfully associates the original called subscriber number, replaces the associated number with the original called subscriber number, triggers the L-iFC, and routes the call to the L-TAS; if the association fails, judging whether the routing number is distributed for the BPF, if so, rejecting the call; the BPF judges whether the routing number is BPF allocated or not, specifically, the BPF judges whether the address information in the routing number is a BPF address or not, and if so, the BPF is allocated.

The BPF routes the call to the L-TAS, and can route the session to the L-TAS according to the routing number; the routing number is distributed by the L-TAS; the L-TAS receives the session invitation message (forwarded by the BPF), finds out the called user number stored when the L-TAS distributes the routing number through the routing number in the message, associates the CS subscription data signed by the called user according to the called user number, and performs service control on the call according to the subscription data.

And the CS subscription data is brought to the L-TAS by the BPF when the third party of the user registers, or is obtained from the HLR to which the user belongs by the L-TAS.

The traffic control includes at least one of: a. the L-TAS triggers the supplementary service according to the subscription of the user; b. the L-TAS triggers the call restriction service according to the operation setting; c. and the L-TAS judges the user call authority according to the user subscription data.

In the following, with reference to the above network structure, how the ICS enhanced network supports conventional CS user roaming according to the present invention is further described in detail.

Fig. 5 is a flow chart illustrating a call initiation procedure of a conventional CS user roaming to an ICS enhanced network according to an embodiment of the present invention, as shown in fig. 5, this embodiment describes that when the conventional CS user roams to the ICS enhanced network for terminating a call, an HLR acquires a roaming number from a BPF, in this embodiment, the BPF allocates the roaming number to the HLR, so that the call is routed to the BPF, and then the BPF calls a called user according to an mAGCF registered by the called user, where this embodiment specifically includes the following steps:

step 501, a traditional CS network gmsc (global System for Mobile communications) sends a routing information request message to HLR, where the message carries a called subscriber number;

step 502, according to the BPF address bound when the user is attached, the HLR applies for a roaming number to the BPF, and the HLR sends a roaming number request message to the BPF through an MAP message, wherein the message carries the number of the called user;

in this step, the roaming number request message is only a message name set by a function, and the message format of the message completely conforms to the MAP message format, and the detailed format of the message is not repeated in the present invention. The message is identified by a protocol or a set identifier, so that the purpose of acquiring the roaming number is achieved.

Step 503, the BPF searches whether the current called user is registered on the BPF by the called user number in the message, and rejects the call if the search fails; if the search is successful, the BPF allocates a routing number pointing to the BPF, wherein the routing number can consist of two parts, one part is a BPF address number and is mainly used for traditional network call routing, the other part is a user number and is used for associating a user data area, after the allocation is successful, the BPF associates the relationship between the routing number and the number of the called user and the user registration data, and the BPF returns the routing number to the HLR through an MAP roaming number response message;

step 504, the HLR sends a routing request response message through the MAP to return the routing number to the GMSC;

step 505, the GMSC routes the call to the BPF according to the routing number, and sends an Initial Address Message (IAM) to the BPF, which may be routed to multiple intermediate network elements due to inter-network roaming, where for convenience of description, the GMSC is directly described to send the Initial IAM Message to the BPF, where the called subscriber number is set as the acquired routing number;

step 506, the BPF receives the call establishment request message or the session request invitation message, associates the original called subscriber number according to the routing number in the message, successfully associates, replaces the association number with the original called subscriber number, triggers the L-iFC, and routes the call to the L-TAS;

the method finds out the user original called user number and user register data area stored before, and triggers the third party service control according to the L-iFC stored in the register data, the triggering mode includes the following steps:

A. the BPF acquires AS address information in the L-iFC;

B. the BPF is matched with a condition for triggering a third-party service in the L-iFC, and whether the current service meets the trigger standard of the L-iFC is judged, wherein the L-iFC is generated by the BPF during user registration according to an operator strategy;

C. if the trigger standard is met, the BPF forwards a session invitation message to an AS address in the L-iFC, wherein the AS address refers to an L-TAS address;

if the association fails, judging whether the routing number is distributed for the BPF, if so, rejecting the call. And judging whether the routing number is distributed by the BPF, namely judging whether the address information in the routing number is the BPF address by the BPF, and if so, distributing the routing number by the BPF.

Step 507, the BPF sends a session invitation message to the L-TAS, wherein the message carries the number of the called user;

step 508, the L-TAS receives the BPF session invitation message, and triggers CS service control according to the CS user data signed by the user, which may specifically include the following:

a. the L-TAS triggers a supplementary service according to the user subscription data;

b. the L-TAS triggers the call restriction service according to the operation strategy of the operator;

c. and the L-TAS judges the call authority of the user according to the user subscription data.

Step 509, after the CS service control is successful, the L-TAS acts as a back-to-back user agent, reestablishes a session, and sends a session invitation message to the BPF

Step 510, the BPF associates user registration information according to the called user number in the message, and sends a session invitation message to the mAGCF according to the mAGCF address information bound in the registration information;

step 511-step 513, the mAGCF pages the user and establishes the called user call connection.

Fig. 6 is a flow chart of a call initiation procedure of a conventional CS user roaming to an ICS enhanced network according to a second embodiment of the present invention, as shown in fig. 6, this embodiment describes that the conventional CS user roams to the ICS enhanced network, and when the conventional CS user terminates a call, an HLR acquires a roaming number from a BPF, and in this embodiment, the BPF acquires the roaming number from an L-TAS, and this embodiment specifically includes the following steps:

601 to 602, and 501 to 502;

step 603, the BPF sends a roaming number request message to the L-TAS, sets the AS address in the L-iFC generated when the called user registers AS the target L-TAS, and sends the roaming number request message to the L-TAS;

step 604, the L-TAS stores the called user number in the received message, and establishes the relationship between the called user number and the routing number, the routing number is composed of an address number and a group of random numbers, wherein the address number is used for calling the routing, and the random numbers are used for associating the stored called user number;

step 605-step 607, the L-TAS transmits the routing number to the GMSC through the response message;

step 608-step 609, the GMSC routes the call to the L-TAS according to the routing number, where the call may pass through other intermediate network elements, for simplicity, it is described herein that the GMSC directly sends an address initial message to the BPF, and if the GMSC approaches a network element supporting the SIP protocol, the BPF may also receive an SIP session invite message;

and step 610, the L-TAS receives the session invitation message, finds out the called user number stored when the L-TAS distributes the routing number through the routing number in the message, associates the CS subscription data signed by the called user according to the called user number, and performs service control on the call according to the subscription data, wherein the CS subscription data is brought to the L-TAS by the BPF when the third party of the user is registered, or is obtained from the HLR to which the user belongs by the L-TAS. The L-TAS performs service control, and the service control may include at least one of the following:

a. the L-TAS triggers a supplementary service according to the user subscription data;

b. the L-TAS triggers the call restriction service according to the operation strategy of the operator;

c. and the L-TAS judges the call authority of the user according to the user subscription data.

Step 611 to step 615, and step 509 to step 513.

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

Claims (16)

1. A user roaming method is characterized in that a marginal proxy function network element BPF is additionally arranged in an IMS centralized service ICS enhanced network; the method comprises the following steps:

after receiving a roaming number request message of a Circuit Switching (CS) domain, the BPF provides a routing number, and a call of the CS domain is routed to the BPF; the BPF provides a routing number, and the routing of the call in the CS domain to the BPF specifically includes: after receiving a roaming number request message sent by a Home Location Register (HLR) to which the user belongs, the BPF determines a routing number pointing to the BPF or the L-TAS and sends the routing number to the HLR; the HLR informs the user of the CS domain, and the user routes the call to the BPF through the routing number;

the BPF routes the call to a local telephone application server L-TAS, and the L-TAS triggers CS service control and serves as a user agent after the service control is successful to establish a session for a called user.

2. The method of claim 1, wherein before the BPF sends the routing number to the HLR, the method further comprises:

the BPF checks whether the called user is registered in the BPF, and rejects the call when the called user is not registered; associating the registration information of the user during registration; the registration information comprises mAGCF address information of a mobile access gateway control function entity and local initial filter control L-iFC information bound during user registration.

3. The method of claim 1, wherein the BPF provides the routing number specifically as:

and the BPF sends a roaming number request message to the L-TAS, and the L-TAS allocates a routing number pointing to the BPF and returns the routing number to the BPF.

4. The method of claim 3, wherein before the L-TAS assigns the routing number, further comprising:

and the L-TAS judges whether the CS subscription data of the called user exists or not, if not, the CS subscription data is acquired through the HLR to which the called user belongs, and the call is rejected when the acquisition fails or the CS subscription data of the called user cannot be acquired.

5. The method of claim 1, further comprising:

and the BPF sets the AS address in the L-iFC generated when the called user registers AS the target L-TAS.

6. The method of any of claims 1 to 5, wherein before the BPF sends a routing number to the HLR, the method further comprises:

and the BPF stores the corresponding relation between the called user number and the routing number in the roaming number request message.

7. The method according to any of claims 1 to 5, wherein said routing number is comprised of an address number and a set of random numbers, wherein said address number is used for call routing and said random numbers are used for storing the called subscriber number in association.

8. The method of claim 1, wherein the BPF routing the call to the L-TAS is specifically:

after receiving a call establishment request message or a session request invitation message, the BPF associates the number of the original called user according to the routing number in the message, and when the association is successful, the number of the original called user is replaced by an associated number, and the L-iFC is triggered to route the call to the L-TAS; and when the association fails, judging whether the routing number is distributed for the BPF, and if so, rejecting the call.

9. The method of claim 1, wherein the BPF routing the call to the L-TAS is specifically:

and the L-TAS receives the session invitation message, finds out the called user number stored when the L-TAS distributes the routing number through the routing number in the message, and performs service control on the call according to the CS subscription data signed by the called user and associated with the called user number.

10. The method of claim 9, wherein the traffic control comprises at least one of:

the L-TAS triggers a supplementary service according to the user subscription data;

the L-TAS triggers a call restriction service according to an operation strategy of an operator;

and the L-TAS judges the call authority of the user according to the user subscription data.

11. An ICS enhanced network is characterized in that the ICS enhanced network comprises a mobile access gateway control function entity (mAGCF), a marginal proxy function network element (BPF) and a local telephone application server (L-TAS); wherein,

the BPF is used for providing a routing number after receiving a roaming number request message of a CS domain, and the call of the CS domain is routed to the BPF; the method is specifically used for determining a routing number pointing to the HLR or the L-TAS after receiving a roaming number request message sent by the HLR to which a user belongs, and sending the routing number to the HLR; the HLR informs the user of the CS domain, and the user routes the call to the BPF through the routing number;

a BPF for routing calls to the L-TAS;

and the L-TAS is used for triggering the CS service control, serving as a user agent after the service control is successful, and establishing a session for a called user.

12. The ICS enhanced network of claim 11, wherein the BPF, before sending the routing number to the HLR, is further configured to check whether the called user is registered at the BPF, and rejects the call when not registered; associating the registration information of the user during registration; the registration information comprises mAGCF address information of a mobile access gateway control function entity and local initial filter control L-iFC information bound during user registration.

13. The ICS enhanced network of claim 11, wherein the BPF is further configured to send a roaming number request message to the L-TAS; the L-TAS is further used for allocating a routing number pointing to the L-TAS and returning the routing number to the BPF.

14. The ICS enhanced network of claim 13, wherein the L-TAS, before allocating the routing number, further determines whether there is CS subscription data of a called subscriber, and if not, acquires the CS subscription data through the HLR to which the called subscriber belongs, and rejects the call if the acquisition fails or the CS subscription data of the called subscriber cannot be acquired.

15. The ICS-enhanced network of claim 11, wherein the BPF, after receiving the call setup request message or the session invitation request message, further associates the original called subscriber number according to the routing number in the message, and when the association is successful, replaces the original called subscriber number with the associated number, triggers the L-iFC, and routes the call to the L-TAS; and when the association fails, judging whether the routing number is distributed for the BPF, and if so, rejecting the call.

16. The ICS-enhanced network of claim 11, wherein the L-TAS, after receiving the session invitation message, finds, through a routing number in the message, a called subscriber number stored when the L-TAS allocates the routing number, and performs service control on the call according to CS subscription data signed by the called subscriber in association with the called subscriber number.