WO2007016863A1 - Procédé et système de commande d'un trajet d'acheminement de session - Google Patents

Procédé et système de commande d'un trajet d'acheminement de session Download PDF

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Publication number
WO2007016863A1
WO2007016863A1 PCT/CN2006/001953 CN2006001953W WO2007016863A1 WO 2007016863 A1 WO2007016863 A1 WO 2007016863A1 CN 2006001953 W CN2006001953 W CN 2006001953W WO 2007016863 A1 WO2007016863 A1 WO 2007016863A1
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WIPO (PCT)
Prior art keywords
domain
call
session
mgcf
information
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PCT/CN2006/001953
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English (en)
French (fr)
Inventor
Dongming Zhu
Xiaoqin Duan
Hai Zhang
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Huawei Technologies Co., Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Priority claimed from CN2005100898345A external-priority patent/CN1913504B/zh
Priority claimed from CN200510089833A external-priority patent/CN100583843C/zh
Application filed by Huawei Technologies Co., Ltd. filed Critical Huawei Technologies Co., Ltd.
Publication of WO2007016863A1 publication Critical patent/WO2007016863A1/zh

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L65/00—Network arrangements, protocols or services for supporting real-time applications in data packet communication
    • H04L65/10—Architectures or entities
    • H04L65/1016—IP multimedia subsystem [IMS]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L65/00—Network arrangements, protocols or services for supporting real-time applications in data packet communication
    • H04L65/1066—Session management
    • H04L65/1083—In-session procedures
    • H04L65/1095—Inter-network session transfer or sharing
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M7/00—Arrangements for interconnection between switching centres
    • H04M7/12—Arrangements for interconnection between switching centres for working between exchanges having different types of switching equipment, e.g. power-driven and step by step or decimal and non-decimal
    • H04M7/1205—Arrangements for interconnection between switching centres for working between exchanges having different types of switching equipment, e.g. power-driven and step by step or decimal and non-decimal where the types of switching equipement comprises PSTN/ISDN equipment and switching equipment of networks other than PSTN/ISDN, e.g. Internet Protocol networks
    • H04M7/125—Details of gateway equipment
    • H04M7/1255—Details of gateway equipment where the switching fabric and the switching logic are decomposed such as in Media Gateway Control

Definitions

  • the present invention relates to the field of network communication technologies, and in particular, to a session routing path control method and system.
  • IMS control static anchoring call control scheme to solve the problem of switching between two domains, such as CS (Circuit Switched) domain and IMS domain.
  • the core technical content of the solution is that for any call/session initiated from the CS domain or the IMS domain, the call/session is triggered to an AS (Application Server) in the IMS domain, and the AS is called by the AS.
  • AS Application Server
  • Session for anchoring control anchoring control
  • subsequent AS handover to the anchored call/session is performed by the AS regardless of the inter-domain handover from the CS domain to the IMS domain or the inter-domain handover from the IMS domain to the CS domain.
  • the AS controls the session, that is, the session is triggered to the AS by defining the iFC.
  • the call initiated by the CS domain triggers the process to the anchor AS.
  • the 3GPP specification currently describes various schemes: For the calling side
  • the initial call initiated for the CS domain that is, for the call initiated by the calling side VMSC (Visit Mobile Switch Center) after receiving the call setup message of the UE, there may be network side routing control using CA ⁇ EL ( Customised Application for Mobile network Enhanced Logic, mobile network enhanced logical user application), and terminal-side routing control using USSD (Unstructured Supplementary Service Data) and Notify (Notification) schemes, the two control modes will
  • CA ⁇ EL Customised Application for Mobile network Enhanced Logic, mobile network enhanced logical user application
  • USSD Unstructured Supplementary Service Data
  • Notification Notification
  • CSAF Cosmetic Switched Adaptation Function
  • the entity with CSAF can be gsmSCF.
  • the entity with CSAF can be an AS.
  • the routing decision entity gsmSCF in the CS domain can be located in the same physical entity as the routing decision entity AS in the IMS domain.
  • the main principle of the anchor control function of the above AS for implementing inter-domain handover is that, when the call is initially established, for example, the UE (A) initiates a call for the UE (B), and the gsmSCF or AS with the CSAF is at the calling side UE.
  • An anchor point AS is inserted in the call path of (A), and the AS enables the B2BUA function to divide the call on the calling side into two segments: an AS termination segment and an AS initiation segment.
  • the AS termination segment is the call segment between the UE (A)-AS
  • the AS initiation segment is the call segment between the AS-UE (B).
  • the AS that performs the anchor control for the current call initiates a new call, and after the AS determines that the inter-domain handover is needed after receiving the call, the AS will initiate the new call initiated by the UE ( ⁇ ').
  • the AS initiates the segment connection, and then releases the call of the AS termination segment.
  • DTF Domain Transfer Function
  • the routing decision point with CSAF gsmSCF or AS can be in the same physical entity as the AS with DTF function.
  • the UE (A) may be a terminal of the CS domain
  • the UE ( ⁇ ') may be a terminal of the IMS domain
  • the call of the UE (A) to the UE ( ⁇ ') enables the same call from the user to the CS. Call continuity between domains to IMS domains.
  • an anchor AS can be inserted in the call path of the calling side UE (B) to implement call control of the inter-domain handover on the subsequent called side.
  • Figure 1 is a flow chart of the CS domain user initiating a call as a calling party, in the network side routing control mode, that is, the CS domain uses the CAMEL mechanism to trigger the initiated call to the AS for anchoring.
  • the VMSC triggers the call to the gsmSCF with CSAF according to the CAMEL subscription information on the calling side.
  • the gsmSCF with CSAF generates a routing number IMRN (IMS Routing Number) pointing to an AS in the IMS domain with DTF functionality, so that the VMSC routes the call to the DTF according to the routing number.
  • IMRN IMS Routing Number
  • the gsmSCF with the CSAF can construct the IMRN by adding the call reference number after the DTF PSI (DTF Public Service Identities DTF), and then the gsmSCF with the CSAF sends the IMRN to the VMSCo through the CAMEL connect message.
  • DTF PSI DTF Public Service Identities DTF
  • the VMSC routes the call to the MGCF (Media Gateway Control Function) in the IMS network to which the calling party belongs according to the IMRN.
  • MGCF Media Gateway Control Function
  • Step 1-5 The MGCF determines that the called information in the IAM message is an IMRN that points to the DTF-enabled AS, and sends an INVITE message to the I-CSCF, where the called information Requested-URI is IMRN.
  • TEL URI present resources identified by telephone numbers, using the resource location identifier described by the phone number) format.
  • the I-CSCF queries the HSS for routing information according to the Requested-URI, and obtains the AS address information associated with the IMRN, that is, the AS address information with the DTF function, and then the I-CSCF forwards the packet to the DTF-enabled AS. INVITE message.
  • the correspondence between the DTF PSI data and the AS address information having the DTF function needs to be configured in the HSS.
  • the HSS may also include DTF PSI information according to the Requested-URI, and then allocate an S-CSCF for the DTF PSI, and The I-CSCF returns the assigned S-CSCF address, and then the I-CSCF forwards the INVITE message to the S-CSCF, and the S-CSCF triggers the INVITE to the DTF-enabled AS according to the iFC.
  • the anchor control is performed, that is, the B2BUA (Back-to-Back User Agent) function is triggered, and the AS reception is terminated.
  • the session and then initiate a new session for the original called information, that is, the AS having the DTF function obtains the S-CSCF information of the calling user side through the Sh interface with the HSS, and then routes the session to the S-CSCF, and The S-CSCF routes the session to the original called side.
  • the S-CSCF executes the ENUM DNS (E.164 Number Domain Name System E.164 Domain Name Conversion System).
  • the conversion function if the original called number can be converted into the SIP URI format, the subsequent call routing is performed in the S domain, and the S-CSCF routes the call to the BGCF of the IMS domain (Breakout Gateway Control Function boundary) The gateway control function), the call is finally routed by the BGCF to the PSTN (Public Switched Telephone Network) or the CS domain via the MGCF, and finally the call is connected to the called party by the PSTN or CS domain.
  • the DTF-enabled AS enables the B2BUA function, for the session terminated in the DTF and the newly initiated session in the DTF, the DTF maintains its call state to control the inter-domain handover that may be initiated by subsequent users.
  • the 3GPP specification provides USSD based on the terminal-side routing control mode (Unstructured Supplementary Service Data unstructured). (additional data services) and two mechanisms based on Notify (notification).
  • the USSD mechanism is applied to the UE not registered to the IMS domain, and when the UE initiates a call to the VMSC, the called address information in the call signaling carries the DTF PSL that points to the DTF-enabled AS, so that the VMSC routes the call to the MGCF. AS with DTF capability in the IMS domain.
  • the actual called information such as the number information of the UE (B) is carried in the USSD signaling sent by the UE to the gsmSCF (Global System for Mobile communications-Service Control Function, gsm service control function) having CSAF.
  • the gsmSCF with the CSAF interacts with the AS with the DTF function to notify the DTF of the real called information of the currently received session, that is, the USSD signaling carries the number information of the UE (B), thereby
  • the AS with the DTF function anchors the received call initiated by the UE, that is, the AS initiates the B2BUA function, terminates the AS receiving the session, and then initiates a new session for the original called information, where the original called information has Obtained in the USSD signaling received by the CSAF's gsmSCF.
  • Subsequent processing routes the session to the called user according to the original called information in the new session initiated by the AS.
  • the Notify mechanism is applied to the UE that has already registered to the IMS domain.
  • the UE initiates a call to the VMSC
  • the called address information in the call signaling carries the DTF PSI of the DTF-enabled AS, so that the VMSC routes the call to the IMS via the MGCF.
  • An AS with DTF capability in the domain An AS with DTF capability in the domain.
  • the real called information such as the number information of the UE (B) is carried in the SIP Notify signaling sent by the UE currently registered to the IMS domain to the AS with the CSAF, so that the AS with the CSAF receives the SEP Notify.
  • the AS interacts with the AS with the DTF function, and notifies the DTF of the current called information of the currently received session, that is, the SIP Notify signaling carries the number information of the UE (B), so that the AS-pair receiving with the DTF function is received.
  • the UE-initiated call is anchored, that is, the AS initiates the B2BUA function, terminates the AS receiving the session, and then initiates a new session for the original called information, where the original called information is received from the SIP with the CSAF. Obtained in Notify signaling.
  • Subsequent processing as described in step 7 of Figure 1, routes the session to the called user according to the original called information in the new session initiated by the AS.
  • the initial call initiated when the called side is the CS domain that is, the GMSC of the called home network, after receiving the call from the calling side, can use the call initiated by the GMSC after analyzing the called information.
  • the CAMEL scheme and signaling interception scheme routes the call to the anchor point AS.
  • the CAMEL scheme is applicable to the case where the GMSC supports the CAMEL capability, and the signaling interception scheme is applicable when the GMSC cannot support the CAMEL capability.
  • 2 is a flow chart in which the CS domain user uses the CAMEL mechanism to trigger a call from the calling side to the anchor AS for anchoring.
  • step 2-1 when the MSISDN of the called information in the call belongs to the CS domain, for the call initiated in the CS domain or the PSTN, the call is routed to the GMSC when the called route is made.
  • step 2-2 After receiving the call from the calling side, the GMSC analyzes the called information, and then the GMSC sends an SRI message to the HLR to obtain routing information of the called user. Because the GMSC supports CAMEL capability, The GMSC sends an SRI message to the HLR carrying the corresponding parameter indicating the CAMEL support information of the GMSC. The HLR returns a called side CAMEL subscription information T-CSI indicating that the user is a CS-S user.
  • the GMSC triggers the CAMEL service according to the received T-CSI, and sends an IDP (intitial) to the gsmSCF with CSAF.
  • Detect Point the initial detection point
  • the gsmSCF with CSAF obtains the current data and status of the user IMS domain from the HSS.
  • the gsmSCF with CSAF obtains the current data and status of the user CS domain from the HLR.
  • the gsmSCF with CSAF generates a routing number IMRN (IMS Routing Number) pointing to an AS in the IMS domain with DTF functionality, so that the GMSC routes the call to the DTF according to the routing number.
  • IMRN IMS Routing Number
  • the gsmSCF with the CSAF may construct the MRN by adding a call reference number after the DTF PSI (DTF Public Service Identities DTF), and then the gsmSCF with the CSAF sends the IMRN to the GMSC through the CAMEL connect message: .
  • DTF PSI DTF Public Service Identities DTF
  • the GMSC routes the call according to the IMRN to the MGCF in the IMS network to which the called user belongs.
  • step 2-10 to step 2-13 after the session information received by the AS having the DTF function includes the IMRN session of the DTF PSI information, the session is anchored, that is, the B2BUA (back-to-back user agent) function is triggered, and the terminal is terminated.
  • the session received by the AS is deleted, and then a new session for the original called information is initiated. That is, the AS having the DTF function obtains the S-CSCF information of the called user side through the Sh interface with the HSS, and then routes the session to the S- CSCF, and the session is routed by the S-CSCF to the original called side.
  • the AS with the DTF function initiates a new session for the original called information
  • the AS with the CSAF needs to perform route analysis on the original called information, and the AS with the CSAF determines that the session needs to be routed to the CS domain.
  • the AS with CSAF constructs the CSRN (CS Routing Number CS domain routing number) in the TEL URI format based on the original called information, and then the called information Requested in the new session initiated by the AS with the DTF function for the original called information.
  • the URI is CSRN.
  • the S-CSCF executes the ENUM DNS (E.164 Number Domain Name System E.164 Domain Name Conversion System).
  • the conversion function if the original called number can be converted into the SIP URI format, the subsequent call routing is performed in the IMS domain; otherwise, the S-CSCF routes the call to the BGCF of the S domain (Breakout Gateway Control Function border gateway control function) ), the call is finally routed by the BGCF to the GMSC of the CS domain via the MGCF, and finally the call is connected by the GMSC to the called party.
  • the DTF-enabled AS enables the B2BUA function
  • the DTF maintains the state for the session terminated in the DTF and the newly initiated session in the DTF to control the inter-domain handover that may be initiated by subsequent users.
  • the GMSC receives the incoming call IAM message of the MGCF, parses the MSISDN of the original called user (using the CAMEL service or other conversion technology), and then, based on the parsed MSISDN, the called information. After the analysis, the GMSC sends an SRI (Sending Routing Info) message to the HLR to obtain the routing information of the called user. Since the GMSC supports the CAMEL capability, the GMSC sends an SRI message to the HLR to carry the corresponding parameter indicating the GMSC. CAMEL support information. The HLR returns a called side CAMEL subscription information T-CSI indicating that the user is a CS-IMS user. Go to steps 2-15 and step 2-3.
  • SRI Send Routing Info
  • the gsmSCF with the CSAF determines that the AS with the DTF function has performed the anchor control on the call, and then no longer allocates the IMRN, and directly sends a continue message to the GMSC.
  • the GMSC continues the subsequent message.
  • the call that is, the GMSC sends an SRI message to the HLR to obtain routing information of the called user (the GMSC carries the suppression T-CSI parameter in the SRI message sent this time), and then the GMSC routes the call according to the routing information of the called user returned by the HLR. After the visitor's visit to the VMSC, the connection is continued.
  • FIG. 3 is a flow chart of the CS domain using a signaling interception mechanism to trigger a call from the calling side to the anchor AS for anchoring.
  • step 3-1 the same step 2-1.
  • the GMSC After receiving the call from the calling side, the GMSC analyzes the called information, and then the GMSC sends an SRI message to the HLR to obtain routing information of the called user, because the GMSC does not support the CAMEL capability. Therefore, the GMSC sends an SRI message to the HLR without carrying corresponding parameters to indicate the CAMEL support information of the GMSC. Therefore, the HLR does not return to the GMSC the called side CAMEL subscription information T-CSI indicating that the user is a CS-IMS user. Instead, the routing information of the called party is directly returned, so that the call cannot be anchored to the DTF-enabled AS in the IMS domain.
  • a signaling intercepting entity SRF (Signalling Relay) is inserted between the GMSC and the HLR. Function signaling forwarding function), the SRF has CSAF, intercepts the SRI message sent by the GMSC to the HLR and analyzes the message, and then performs corresponding inter-domain routing policy control processing.
  • the SRF with CSAF obtains the current data and status of the user IMS domain from the HSS.
  • the SRF with CSAF obtains the current data and status of the user CS domain from the HLR.
  • the SRF with CSAF generates a routing number that points to an AS with DTF capability in the IMS domain.
  • the gsmSCF with CSAF may construct an IMRN by adding a call reference number after the DTF PSI (DTF Public Service Identities DTF), and then the SRF with CSAF mimics the function of the HLR and returns an SRI-Ack message to the GMSC.
  • the SRI-Ack message sends the IMRN as the called routing information to the GMSC.
  • the GMSC After the GMSC receives the incoming call IAM message of the MGCF, the GMSC parses the MSISDN of the original called user by using a certain conversion technology, and then analyzes the called information based on the parsed MSISDN, and then sends the GMSC to the HLR.
  • the SRI message obtains routing information of the called user.
  • the call is also intercepted by the SRF with CSAF. If the SRF with CSAF determines that the call has been processed, the intercepted SRI is not analyzed, and the corresponding inter-domain routing policy control processing is not performed, directly to the HLR.
  • the SW message is forwarded, and the received SRI-Ack message returned by the HLR is forwarded to the GMSC. Then, the GMSC routes the call to the visited VMSC of the called user according to the received routing information of the called user in the SRI-Ack.
  • the operator can assign a corresponding MSISDN number to the user of the IMS domain when the number is assigned by the operator, so as to implement a call initiated by the CS domain or the PSTN user to the IMS domain user. Therefore, when a user in the CS domain or the PSTN calls an MSISDN user in the IMS domain, the CS domain or PSTN user initiated call needs to be routed to the called user's home IMS domain.
  • the AS with DTF function performs anchoring of the call, and the AS controls the inter-domain handover that may be initiated by subsequent users.
  • the GMSC After the GMSC receives the incoming call IAM message of the MGCF, the GMSC can use some conversion technology to parse the MSISDN of the original called user, and then, after analyzing the called information based on the parsed MSISDN, the GMSC The HLR sends an SRI message to obtain routing information of the called user.
  • the call is also intercepted by the SRF with CSAF. If the SRF with CSAF determines that the call has been processed, the intercepted SRI is not analyzed, and the corresponding inter-domain routing policy control processing is not performed, directly to the HLR.
  • the SRI message is forwarded and the SRI-Ack message returned by the HLR it receives is forwarded to the GMSC.
  • the GMSC routes the call to the visited VMSC of the called user according to the received routing information of the called user in the SRI-Ack.
  • CS domain 4 is a calling user of a CS domain or a PSTN, and when an MSISDN user in the IMS domain is a called user, the CS domain or the PSTN network routes the call to the IMS domain and triggers to the anchor AS according to the analysis of the called number.
  • step 4-1 since the MSISDN of the called user belongs to the S domain, the CS domain or the PSTN network that initiates the call routes the call to the MGCF in the IMS domain of the called user.
  • the MGCF converts the MSISDN into a TELURI, and sends an INVITE message to the I-CSCF.
  • the called information Requested-U I in the message is the TEL URI format of the called MSISDN.
  • the I-CSCF queries the HSS for routing information according to the Requested-URI, and obtains the registration of the user in the IMS domain.
  • the S-CSCF address information, and the session is routed to the corresponding S-CSCF. If the current user is not registered to the IMS domain, the Ijl-CSCF routes the session to an S-CSCF temporarily allocated for the unregistered user.
  • the S-CSCF triggers the session to an AS with CSAF based on iFC (initial Filter Criteria).
  • the AS with CSAF obtains the registration status and data of the current IMS domain of the user from the HSS.
  • the AS with CSAF obtains the registration status and data of the current CS domain of the user from the HLR.
  • the AS with CSAF performs route analysis on the called information.
  • the AS with CSAF determines that the session needs to be routed to the CS domain for connection, the AS with CSAF constructs the TEL URI based on the original called information.
  • the format of CSRN CS Routing Number CS domain routing number
  • the AS with DTF function anchors the session received by the AS with CSAF, that is, triggers.
  • the B2BUA Back-to-Back User Agent
  • the B2BUA Back-to-Back User Agent
  • the called information Requested-URI in the new session is the CSRN of the AS structure with CSAF. That is, the AS having the DTF function obtains the S-CSCF information of the called user side through the Sh interface with the HSS, and then routes the session to the S-CSCF, and the session is routed by the S-CSCF to the original called side.
  • the Requested-URI is CSRN.
  • the S-CSCF cannot convert it to the SIP URI format. Therefore, the S-CSCF routes the session to the BGCF of the IMS domain, and the BGCF finally routes the session to the CS domain via the MGCF. GMSC.
  • the DTF When the DTF-enabled AS enables the B2BUA function, the DTF maintains the state for the session terminated in the DTF and the newly initiated session in the DTF to control the inter-domain handover that may be initiated by subsequent users.
  • the GMSC receives the incoming call IAM message of the MGCF, and then parses the MSISDN of the original called user. After the CAMEL service or other conversion technology is used, and then the called information is analyzed based on the parsed MSISDN, the GMSC sends an SRI message to the HLR to obtain routing information of the called user. Since the GMSC supports the CAMEL capability, The GMSC sends an SRI message to the HLR carrying the corresponding parameter indicating the CAMEL support information of the GMSC. The HLR returns a called side CAMEL subscription information T-CSI indicating that the user is a CS-S user.
  • step 4- ⁇ same as step 2-3.
  • the gsmSCF with the CSAF determines that the AS with the DTF function has anchored the call, and then no longer allocates the IMRN, and directly sends a continue message to the GMSC. After receiving the continue message, the GMSC continues the subsequent message.
  • the call that is, the GMSC sends an SRI message to the HLR to obtain routing information of the called user (the GMSC carries the suppression T-CSI parameter in the SRI message sent this time), and then the GMSC routes the call according to the routing information of the called user returned by the HLR. After the visitor's visit to the VMSC, the connection is continued.
  • the initiated call needs to be initiated from the CS domain.
  • the VMSC in the calling area of the calling party routes to the AS with the DTF function in the calling home IMS domain, and the AS anchors the call and performs subsequent possible inter-domain handover control.
  • the AS with the DTF function anchors the call
  • the AS with the CSAF performs route analysis on the original original called information in the call initiated by the original calling party to the CS domain, and the AS with the CSAF determines that the original call needs to be routed.
  • the CSRN When the CS domain is returned, the CSRN is generated according to the original called information, and then the DTF function is triggered.
  • the AS with the DTF function routes the call back to the CS domain to which the called party belongs according to the CSRN.
  • the entire call path for the initial call initiated when the calling side is the CS domain is the CS domain of the calling party -> the IMS domain of the calling party - the CS domain to which the called party belongs, so that the bearer in the call path is established.
  • the way is DTM Bearer -> IP Bearer -> DTM Bearer.
  • the call received by the GMSC in the called home CS domain needs to be routed to the DTF-enabled AS in the called home IMS domain, by the AS.
  • Anchor the call and perform subsequent possible inter-domain handover control.
  • the AS with the DTF function anchors the call
  • the AS with the CSAF makes a routing decision on the original original called information in the call initiated by the original called CS domain.
  • the AS with the CSAF determines the original call needs to be routed.
  • the CSRN is generated according to the original called information, and then the DTF function is triggered.
  • the AS having the DTF function routes the call back to the CS domain called by the CSRN.
  • the entire call path for the initial call initiated when the called side is the CS domain is the CS domain to which the called party belongs - the IMS domain to which the called party belongs - the CS domain to be called, and thus the established bearer in the call path.
  • the way is DTM Bearer -> IP Bearer -> DTM Bearer.
  • the process in which the calling user A in the CS domain calls the called user B in the CS domain can be succinctly expressed as: A (calling visited CS domain) -> B (called called CS domain) -> B (called called CS domain), the establishment mode of the bearer in the call path is: DTM bearer -> DTM bearer.
  • the call process changes to: A (calling visited CS domain) -> A (calling home IMS domain) -> B (called party CS domain) -> B (called called CS domain), so that the establishment mode of the bearer in the call path is changed to: DTM bearer -> IP 7?
  • the call process changes to: A (caller visited CS domain) -> B (called home CS domain) -> B (called home IMS domain) -> B (called called CS domain), and thus carried in the call path
  • the establishment mode is changed to: DTM bearer -> IP bearer -> DTM bearer; If anchor timing is required for both the calling and called sides, the call process is changed to: A (calling visited CS domain) -> A (calling home IMS) Domain) ->B (called by attribution) CS domain) -> B (called the home IMS domain) -> B (called the CS domain), so that the establishment mode of the bearer in the call path is changed to: DTM bearer -> IP bearer -> DTM bearer -> DTM bearer - >IP Bearer ->DTM Bearer.
  • one or more IP bearer routes are inserted in the simple DTM bearer route due to the introduction of the static anchor scheme.
  • the voice codec conversion is required. Since the conversion of the voice codec will reduce the quality of the voice service, the multiple voice codec conversion introduced by the static anchor scheme will seriously affect the original voice. Quality of business.
  • IP bearer routes are inserted into the simple DTM bearer route. Since the IP bearer can effectively utilize the network resources, it can further Optimize the routing path of the session, extend the imported DP bearer path as much as possible, and reduce the DTM bearer path to reduce the network operation cost.
  • the initiated call needs to be routed from the VMSC of the calling site in the CS domain to the DTF-enabled AS in the calling home IMS domain, and the call is anchored by the AS. And performing subsequent inter-domain handover control.
  • the MGCF in the VMSC of the calling party and the calling home MS domain.
  • a DTM bearer is established between the MGWs. This established DTM bearer is introduced because it implements a call control scheme for static anchors, thus generating a route bypass of the DTM bearer.
  • the initiated call needs to be routed from the GMSC in the CS domain to the DTF-enabled AS in the called home IMS domain, and the AS is anchored and subsequently performed.
  • Inter-domain handover control where a DTM bearer needs to be established between the GMSC and the MGW under the control of the MGCF in the called home IMS domain, in order to implement the routing of the CS domain call to the DTF-enabled AS in the IMS domain.
  • the established DTM bearer is also introduced due to the call control scheme for implementing the static anchor point. Therefore, the route bypass of the DTM bearer is also generated. Summary of the invention
  • the routing path control of the call of the domain such as the nearest routing control, etc.; the invention reduces the number of voice codec conversions caused by the DTM bearer and the IP bearer conversion between the CS domain and the MS domain, and avoids the degradation of the voice service quality;
  • the invention also realizes the purpose of saving the DTM bearer, optimizing the DTM bearer between the CS domain and the IMS domain, and improving the utilization of the IP bearer.
  • the present invention provides a session routing path control method.
  • the method includes the following steps:
  • the application server determines a network entity in the IMS domain corresponding to the session
  • the application server provides the service call session control function S-CSCF with the network entity information in the IMS domain determined by the S-CSCF, and the session is routed by the S-CSCF to the network entity in the IMS domain;
  • the network entity in the IMS domain routes the session to a network entity in the circuit switched domain.
  • the circuit switched domain is: a circuit switched CS domain of a mobile network, or a CS domain of a public switched telephone network PSTN.
  • the step a specifically includes: The application server determines, according to the predetermined bearer optimization policy, the network entity in the IMS domain corresponding to the session.
  • the call that needs to be routed from the IMS domain to the circuit switched domain includes: a calling side session initiated in the IMS domain when the called party is a circuit switched domain user, or a circuit switched domain that needs to perform an anchoring process in the IMS domain
  • the called party initiates an initial call.
  • the predetermined bearer optimization policy in the step a is: the same as the media gateway control function MGCF that the session has been traversed; and the step a specifically includes:
  • the application server obtains the MGCF that the call corresponding to the session passes when it is routed from the circuit switched domain to the IMS domain.
  • the application server determines the MGCF as the network entity information in the IMS domain corresponding to the session.
  • the MGCF that the call passes when routing from the circuit switched domain to the IMS is determined by the application server according to a predetermined policy.
  • the predetermined strategy in step al includes: S is the nearest routing policy.
  • the step a1 specifically includes -al2, the MGCF carries its information in the invite INVITE message, and transmits the message to the application server through the S-CSCF; the al3 application server determines the information of the MGCF carried in the INVITE message as needing to be routed to The information of the MGCF that the session of the CS domain once routed.
  • the INVITE message of the step al2 further includes: The MGCF allocates a call reference number for the session, and the call reference number is used to identify the session.
  • the step b specifically includes: the application server constructs a CS domain routing number CSRN according to the MGCF information, and sends the CS domain routing number to the S-CSCF; the S-CSCF routes the session to the MGCF according to the MGCF information in the CSRN. .
  • the CSRN includes: MGCF routing information and original called information; or the CSRN includes: MGCF routing information and original called information and a call reference number.
  • the step c further includes: the MGCF acquires a call reference number of the session forwarded by the S-CSCF, and determines, according to the call reference number, that the session is a previously routed session, and controls the media gateway function MGW not to talk to the outgoing call and the incoming call. Perform codec conversion.
  • the predetermined bearer optimization policy in the step a is: the MGCF that is the closest to the current MSC of the called user; and the step a specifically includes: the application server acquiring the current state of the called user that needs to be routed to the session of the mobile network circuit switched CS domain.
  • the step b specifically includes: the application server constructs the CSRN according to the MGCF information, and sends the CSRN to the S-CSCF; the S-CSCF determines, according to the MGCF information, that the session that needs to be routed to the circuit switched domain needs to be routed across the IMS domain.
  • the session is routed to the MGCF through the border gateway control function BGCF of the IMS domain in which it is located, and the BGCF of the user visited place.
  • the step c specifically includes: obtaining, by the MGCF of the gateway mobile switching center GMSC, routing information of the called user of the mobile network circuit switched CS domain from the home location register HLR, and directly routing the session to the called party according to the routing information.
  • the predetermined bearer optimization policy in the step a includes: the MGCF that is the same as the MGCF that the session has traversed or the closest to the current MSC of the called user; and the step a specifically includes: the application service selects a predetermined one according to the predetermined rule. Carrying an optimization policy, and determining a network entity in the IMS domain corresponding to the session that needs to be routed to the circuit switched domain according to the selected bearer optimization policy.
  • Steps of selecting a predetermined bearer optimization policy according to a predetermined rule by the application server in the IMS domain in the step a The application server selects a predetermined bearer optimization policy according to the user preference setting; and/or the application server selects a predetermined bearer optimization policy according to the location information of the called user in the circuit switched domain.
  • the user preference setting specifically includes: when the INVITE message received by the application server carries the RN, selects the same bearer optimization policy as the MGCF that the session has been routed; and the used INVITE message received by the application server carries the use phone.
  • the resource location identifier Tel URI H of the number description selects the bearer optimization policy of the MGCF that is closest to the current MSC of the called user.
  • the application server is: an application server having an inter-domain routing function in an IMS domain.
  • the present invention provides a session routing path control system, including: a network entity determining module located in an application server: determining, for a session that needs to be routed from the IMS domain to the circuit switched domain, a network entity in the IMS domain corresponding to the session;
  • An IMS intra-domain routing module located in the IMS domain acquiring network entity information in the IMS domain determined by the network entity determining module, and routing the session that needs to be routed to the circuit switched domain to the IMS domain network according to the network entity information Entity
  • the inter-domain routing module located in the IMS domain network entity obtains network entity information that needs to be routed to the circuit switched domain, and routes the forwarded session of the routing module in the IMS domain to the network entity in the circuit switched domain.
  • the cross-domain routing module of the network entity located in the IMS domain further includes:
  • the IMS domain function sub-module receives the session forwarded by the routing module in the IMS domain, and routes it to the circuit switched domain function sub-module; the circuit-switched domain function sub-module: analyzes the route of the called user in the circuit-switched domain, and according to the route The analysis routes the session to the switching center where the called user is currently located.
  • the present invention also provides a routing path control method for a call that needs to be routed from a circuit switched domain to an IMS domain, the method comprising the steps of:
  • the application server determines a network entity in the IMS domain corresponding to the call;
  • the application server provides the network entity in the circuit switched domain with its determined network entity information in the IMS domain; c. the network entity in the circuit switched domain routes the call to the network in the IMS domain entity.
  • the call that needs to be routed from the circuit switched domain to the IMS domain includes calls that need to be in the circuit switched domain of the anchoring process in the IMS domain.
  • the application server is: an application server with inter-domain routing function in the IMS domain, or a gsm service control function gsmSCF with inter-domain routing function in the CS domain of the mobile network, or a signaling forwarding function SRF with inter-domain routing function. .
  • the step a further includes:
  • the MSC initiating the initial call in the CS domain triggers the call to the application server according to a predetermined trigger mechanism
  • the application server determines, according to a predetermined policy, information that needs to be routed to the MGCF in the IMS domain.
  • the originating initial call in the mobile network circuit switching CS domain is: when the calling side is the CS domain, when the VMSC receives the call initiated by the call setup message of the user equipment UE, or the called side is the CS domain, the GMSC is receiving After the call from the calling side, the call initiated after analyzing the called information;
  • the predetermined triggering mechanism is: a mobile network enhanced logical user application CAMEL mechanism, or an unstructured supplementary service data USSD mechanism, or a Notify mechanism, or a signaling interception mechanism.
  • the step a2 specifically includes: the application server acquiring location information of the calling side VMSC in the CS domain of the mobile network, and determining the MGCF closest to the VMSC according to the nearest policy; or acquiring the mobile network circuit by the application server Exchanging the current location information of the calling user in the CS domain, and determining the MGCF closest to the current VMSC of the calling user according to the nearest policy, or the application server acquiring the location of the called side GMSC in the mobile network circuit switched CS domain Information, and determining the MGCF corresponding to the GMSC according to a predetermined proximity policy.
  • the step of the application server acquiring the mobile station circuit switching location information of the calling side VMSC in the CS domain includes:
  • the application server determines location information of the calling side VMSC in the CS domain according to the MSC address information carried in the CAMEL initial detection point IDP message.
  • the step of the application server acquiring the location information of the called side GMSC in the circuit switched CS domain of the mobile network comprises: determining, by the application server, the location of the called side GMSC in the CS circuit of the mobile network according to the MSC address information carried in the CAMEL IDP message Information; or
  • the application server determines location information of the called side GMSC in the circuit switched CS domain of the mobile network according to the MSC address information carried in the SRI message.
  • the step b specifically includes: the application server constructs an IMS domain routing number IMRN according to the MGCF information, and sends the IMS domain routing number IMRN to the VMSC/GMSC; or the application server constructs an IMRN according to the MGCF information, and Sending to the UE, the UE provides the IMRN to the VMSC where it is currently located when the call is initiated.
  • the IMRN includes: MGCF routing information and inter-domain transfer function public service identifier DTF PSI and call reference number; or the IMRN includes: MGCF routing information and DTF PSI.
  • the step a further includes: when the network entity MGCF in the IMS domain determined by the application server does not belong to the network entity in the home IMS domain, the MGCF performs the E.DNS domain name conversion system ENUM DNS conversion function on the called information.
  • the query CSCF I-CSCF address information in the home IMS domain is determined.
  • the routing path control system provided by the present invention includes:
  • the routing module located in the circuit switched domain: determines the IMS domain network entity information provided by the module according to the IMS domain network entity, and routes the call to the corresponding entity in the IMS domain.
  • the application server provided by the present invention, wherein the application server is provided with an IMS domain network entity determining module, and for a call that needs to be routed from the circuit switched domain to the IMS domain, the IMS domain network entity determining module determines that the call needs to be routed according to a predetermined policy. a network entity in the IMS domain to the network entity in the IMS domain and to the network entity in the circuit switched domain.
  • the switching center provided by the present invention is disposed in a circuit switching domain, and the routing center is provided with a routing module, and the routing module routes the call to the corresponding network entity in the IMS domain according to the MS domain network entity information provided by the application server. .
  • the application server in the present invention can control the routing path of the session from the IMS domain to the CS domain according to the specific routing path control requirement in the network. For example, when a session routed from the CS domain to the IMS domain needs to be routed back to the CS domain from the IMS domain, the application server can route the session back to the network entity in the MS domain that it once routed according to the bearer optimization policy. CS domain, and by the once routed The network entity in the MS domain controls the voice codec conversion between the DTM bearer and the IP bearer in the inbound and outbound sessions of the same session.
  • the IP bearer path introduced in the static anchor scheme is eliminated.
  • the number of voice codec conversions carried in the routing process from the CS domain to the IMS domain to the CS domain is avoided, which avoids the degradation of voice service quality.
  • the application server For example, for a session that needs to be routed from the IMS domain to the CS domain, the application server The session can be routed to the MGCF that is closest to the network entity in the CS domain according to the bearer optimization policy, and then the MGCF transfers the session to the CS domain, thereby extending the IP bearer path in the IMS domain as much as possible, and reducing the DTM bearer path.
  • the utilization of the IP bearer is improved.
  • the present invention When the present invention is applied to the static error point scheme under the call continuity problem, the number of voice codec conversions between the DTM bearer and the IP bearer caused by the static anchor scheme can be effectively reduced.
  • the impact of the static anchor scheme on the voice service quality is reduced, and the imported IP bearer is extended as much as possible by optimizing the routing path of the session. Diameter, reducing DTM bearer path.
  • the application server in the present invention controls the call from the circuit switched domain to the IMS domain routing path according to a predetermined route optimization policy, so that the network entity in the circuit switched domain can be applied.
  • the routing control of the server routes the call from the network entity in the specified IMS domain to the IMS domain. If the application server sets the nearest routing policy, the application server obtains the location information of the calling network entity in the circuit switched domain, and determines the distance.
  • the circuit switched domain initiates a network entity in the nearest IMS domain of the calling network entity, and then the application server provides routing information to the network entity in the IMS domain to the originating network entity in the circuit switched domain, so that the network entity in the circuit switched domain can According to the obtained routing information, the call is routed from the designated IMS domain network entity to the IMS domain, so that the path of the DTM bearer between the CS domain and the IMS domain is the shortest, thereby saving the DTM bearer and reducing the possible route bypass;
  • the invention is applied to static anchor points under the topic of call continuity When the case, effectively reduces the static anchoring DTM bearer detour route scheme introduced.
  • Figure 1 is a flow chart of triggering a call initiated by a CS domain to a DTF-enabled AS using a CAMEL mechanism when a user in the CS domain initiates a call as a caller;
  • FIG. 2 is a flow chart of triggering an incoming call to an AS with a DTF function by using a CAMEL mechanism in a CS domain when a user in the CS domain is called;
  • Figure 3 is a flow chart of the CS domain user using the signaling interception mechanism to trigger the incoming call to the DTF-enabled AS for anchoring when the user in the CS domain is called.
  • Figure 4 When a user in the CS domain or network is the calling user, when the MSISDN user in the IMS domain is the called user, the CS domain or the PSTN network routes the call to the IMS domain and triggers to the anchor AS according to the analysis of the called number.
  • Flow chart for anchoring When a user in the CS domain or network is the calling user, when the MSISDN user in the IMS domain is the called user, the CS domain or the PSTN network routes the call to the IMS domain and triggers to the anchor AS according to the analysis of the called number.
  • FIG. 5 is a schematic diagram 1 of a session routing path control system according to an embodiment of the present invention.
  • FIG. 6 is a schematic diagram of DTM bearer optimization according to an embodiment of the present invention.
  • FIG. 7 is a second schematic diagram of a session routing path control system according to an embodiment of the present invention. Mode for carrying out the invention
  • the first core technical content of the present invention is when the session needs to be routed from the IMS domain to the circuit switched domain, if the application server
  • the ability to control the routing path of the session according to the predetermined routing policy can achieve different purposes for route optimization or bearer optimization, for example, in the static anchor scheme under the call continuity topic, if the MGCF in the IMS domain can route the session nearby
  • the IP bearer path introduced by the static anchor scheme can be extended as much as possible, the DTM bearer path is reduced, and the DTM bearer path of the session is optimized; if the session can be routed from the IMS network entity it once routed Back to the circuit switched domain, the IP bearer path introduced under the static anchor scheme can be eliminated, and the number of codec conversions during the routing process from the circuit switched domain to the IMS domain to the circuit switched domain is effectively reduced.
  • the GMSC uses the network side controlled CAMEL mechanism or signaling interception mechanism to trigger the initiated call to the gsmSCF or SR with CSAF.
  • the routing control of the call, and then the gsmSCF or the SRF with the CSAF generates a routing number IMRN that points to an AS in the IMS domain with the DTF function according to a certain routing policy, and delivers the IMRN using the CAMLE connect operation or the SRI-Ack message.
  • GMSC uses the network side controlled CAMEL mechanism or signaling interception mechanism to trigger the initiated call to the gsmSCF or SR with CSAF.
  • the routing control of the call, and then the gsmSCF or the SRF with the CSAF generates a routing number IMRN that points to an AS in the IMS domain with the DTF function according to a certain routing policy, and delivers the IMRN using the CAMLE connect operation or the SRI-Ack message.
  • the gsmSCF or SRF with CSAF in addition to the need to ensure that the allocated IMRN can point to a DTF-capable AS, also needs to ensure that the GMSC can fix the call to an MGCF in an IMS domain according to its assigned IMRN.
  • the GMSC then sends an IAM message to the MGCF according to the IMRN, routing the call to the IMS domain.
  • the subsequent MGCF forwards the session to the AS with the DTF function according to the IMRN.
  • the session information received by the AS with the DTF function includes the IMRN session of the DTF PSI information, the session is anchored, that is, the B2BUA function is triggered.
  • Terminating the session received by the AS, and then initiating a new session for the original called party information that is, the AS having the DTF function obtains the S-CSCF information of the called user side through the Sh interface with the HSS, and then routes the session to The S-CSCF, and the session is routed by the S-CSCF to the original called side.
  • the AS with the DTF function initiates a new session for the original called information
  • the AS with the CSAF needs to perform route analysis on the original called information, and the AS with the CSAF determines that the session needs to be routed to the mobile network circuit switching.
  • the AS with the CSAF constructs the CSRN in the TEL URI format based on the original called information, and then the called information Requested-URI in the new session initiated by the AS with the DTF function for the original called information is CSRN.
  • the CS allocated by the AS with CSAF needs to be able to ensure that the S-CSCF on the called subscriber side can route the session back to the same MGCF as the GMSC uses the MRN to route the call to the IMS domain. Then, the MGCF routes the call to the GMSC according to the CSRN.
  • the MGCF determines that the call it has received, that is, the IAM message sent by the GMSC received by the MGCF, and the call originated by itself, that is, the IAM message sent by the MGCF to the GMSC belongs to the same call, the MGCF controls the MGW to enter the call.
  • the outgoing call session is not subjected to codec conversion, that is, the MGCF controls the MGW not to convert its DTM bearer into an IP bearer for the received IAM message sent by the GMSC, and the MGCF controls the MGW to directly use its previous reception for the IAM message sent to the GMSC.
  • the DTM bearer is received, so that the voice service initiated by the GMSC to the DTM bearer of the MGW can be non-destructively connected to the voice service initiated by the MGW to the DTM bearer of the GMSC.
  • the above-mentioned IMR with CSAF or the IRF allocated by the SRF needs to be able to ensure that the GMSC can selectively select the MGCF in an IMS domain.
  • the process can be implemented by the RN.
  • the IMRN can be configured as a "route prefix + DTF PSI + call reference number". Mode, according to the routing prefix, the GMSC can be fixedly addressed to a specified MGCF in the IMS domain.
  • the above-mentioned CSR with CSAF allocation needs to be able to ensure that the process of routing the session back to the same MGCF as the GMSC uses the IMR to route the call to the IMS domain can be implemented by the configuration of the CSRN.
  • the CSRN can be configured as a "route”.
  • the prefix + original called information + call reference number", according to the routing prefix S-CSCF can be fixedly addressed to a specified MGCF in the IMS domain.
  • the MGCF determines that the call received by the MGCF, that is, the IAM message sent by the GMSC received by the MGCF, and the call sent by itself, that is, the IAM message sent by the MGCF to the GMSC belongs to the same call, can be judged by the call.
  • the called information that is, the call reference number in the CSRN and the called information in the received call, that is, the call reference number in the IMRN are determined to be the same.
  • the MGCF may also determine the INVITE message sent by the MGCF to the AS with the DTF function according to the IMRN, and the INVITE message sent by the received session, that is, the AS having the DTF function, according to the CSRN to the MGCF. Determine if two sessions belong to the same session. Similarly, it can be determined by judging whether the called information in the session sent by the MGCF, that is, the call reference number in the IMRN and the called information in the session received by the MGCF, that is, the call reference number in the CSRN are the same.
  • the MGCF can also add relevant parameters in the session information sent by itself, and the AS with the DTF function passes the relevant parameters added by the MGCF in the newly initiated session, so that the MGCF judges the session it sends and the session it receives. Whether to include the same related parameter information to determine whether the two sessions belong to the same session.
  • the MGCF can add its own assigned call reference number in the master/called message in the session that it sends, and then send the session to the DTF-enabled AS through the I-CSCF.
  • the DTF-enabled AS triggers the B2BUA function. Terminating the session received by the AS, and then initiating a new session for the original called information.
  • the primary/called information in the new session also includes the call reference number assigned by the MGCF, and then the new session is sent to the S-CSCF. Forward to the same MGCF. Therefore, the MGCF determines whether the call reference number in the master/called party information in the session that is sent and the call reference number in the master/called party information in the received session are the same, to determine whether the two sessions belong to The same session.
  • the MGCF may include the MGW information of the one selected by the GMSC when sending the IAM message to the MGCF in the call reference number, so that when the MGCF receives the session sent by the S-CSCF to the MGCF,
  • the MGCF determines that the MGCF determines that the call received by itself and the call originated by itself belong to the same call
  • the MGCF further controls the session to select the same MGW as the previous call according to the MGW information in the call reference number information.
  • the MGCF controls the MGW not to perform codec conversion on the inbound and outbound sessions.
  • the application server determines that the IMS domain network entity starts from reducing the number of codec conversions to ensure the quality of the voice service. Therefore, the MGCF needs to associate the two segments of the incoming IMS domain and the outgoing IMS domain under the same call.
  • the control MGW does not perform codec conversion on the inbound and outbound sessions.
  • the DTM bearer path is further described.
  • the application server can control the routing path of the session according to the predetermined routing policy, different routing optimization or bearer optimization can be achieved, such as in the call continuity topic.
  • the static anchor scheme if the MGCF in the IMS domain can route the call to the VMSC/GMSC in the CS domain, the DTM bearer path can be shortened as much as possible, the use of the IP bearer is prolonged, and the live DTM is optimized. Bearer path.
  • the AS with the CSAF can allocate the CSRN, considering the location information of the called party in the circuit switched domain, and the allocated CSRN can The session of the S domain is routed to the MGCF that is closest to the VMSC where the current called party is located, so that the session can be far out of the IMS domain, and subsequent calls are connected between the MGCF and the VMSC, thereby prolonging the used BP bearer and shortening the DTM bearer. Increase the utilization of IP bearers and reduce network operation costs for operators.
  • the AS with the CSAF in the allocated CSRN takes into account that the location information of the called user in the CS domain can be obtained by the AS with the CSAF querying the HLR of the called user for the current registration state of the called user, that is, with the CSAF.
  • the AS sends an ATI (Any Time Interrogation) implementation to the HLR.
  • the AS with CSAF can determine the location information of the user based on the Location Information information in the ATI Ack message returned by the HLR.
  • the above-mentioned CSRN allocated by the AS with CSAF can route the activity of the IMS domain to the current location of the current called party.
  • the recent MGCF of the VMSC enables the session to be far out of the IMS domain through the composition of the CSR:
  • the composition of the CSRN can be "route prefix + original called information + call reference number", and the AS with CSAF is
  • the CSRN is allocated, the location information of the current mobile network circuit switched CS domain of the called subscriber is referenced, and the routing prefix of the MGCF that can be addressed to the VMSC closest to the current mobile network circuit switched CS domain of the called subscriber is allocated.
  • the configuration of the CSRN may be directly in the form of an MSRN, that is, the AS with the CSAF that allocates the CSRN directly sends a roaming number operation to the HLR on the called side, acquires the MSRK of the called user, and directly calls the call from the CSAF according to the MSRN. It is routed to the VMSC where the user is currently located via the S-CSCF and the MGCF.
  • the S-CSCF selects the MGCF according to the routing prefix of the CSRN or the MSRN obtained by the AS with the CSAF
  • the S-CSCF determines, according to the routing prefix of the CRSN, that the MGCF that needs to be routed does not belong to the IMS domain, that is, the IMS domain to which the user belongs. If the user's home MS domain cannot be overlaid to the mobile network circuit switched CS domain that the user is currently visiting, then the cross-IMS domain needs to be routed. Then the S-CSCF selects the BGCF of the IMS domain and routes the session to the BGCF.
  • the BGCF of the local domain routes the call to the BGCF in the IMS domain of the user visited according to the routing prefix of the CSRN or the MSRN, and the BGCF in the IMS domain of the subsequent user visited is addressed to the current VMSC of the user according to the routing prefix or the MSRN.
  • the MGCF in the IMS domain of the nearest user visits, and then routes the call to the MGCF.
  • the MGCF forwards the call to the CS-domain entity of the mobile network in which the called user is currently located according to the original called information, that is, the MGCF is in accordance with the CSR.
  • the original called information forwards the call to the GMSC of the circuit-switched CS domain of the mobile network where the called user is currently located, or forwards the call to the called user according to the MSRN.
  • the mobile network circuit exchanges the VMSC of the CS domain.
  • the MGCF when the MGCF is forwarding the call according to the original called information in the CSRN, the MGCF needs to perform the called route analysis according to the called information when receiving the session forwarded by the S-CSCF or the BGCF, in order to avoid the MGCF pair.
  • the call is sent back to the GMSC of the circuitized CS domain of the called mobile home network.
  • the MGCF After receiving the INVITE message of the S-CSCF/BGCF, the MGCF needs to also act as the GMSC to complete the mobile to the HLR.
  • the network circuit switched CS domain called user takes the roaming number operation and acquires the user's MSRN. According to the MSRN, the call is directly routed from the MGCF/GMSC to the VMSC where the user is currently located.
  • the MGCF receives the INVITE message of the S-CSCF or the BGCF, and when establishing the DTM bearer, according to the obtained routing information of the user, that is, the MGCF serves as the GMSC.
  • the HLR completes the operation of the mobile network circuit switched CS domain called user to obtain the roaming number operation to obtain the MSRN where the user is currently located, thereby determining the current VMSC address information of the called user, and the MGCF selects the MGW closest to the VMSC to establish the MGW to the VMSC.
  • the inter-DTM bearer so that the DTM bearer established between the VMSC and the MGW is the shortest, further optimizes the call by the mobile network circuit-switched CS domain route to the DTM bearer between the MS domains.
  • the following is a description of a technical solution for effectively reducing the number of codec conversions based on the content of the first core technology provided by the present invention as an example of a called side session that requires static anchoring in the IMS domain.
  • the application server of the present invention is an AS with inter-domain routing control function in the IMS domain, that is, an AS with CSAF.
  • the network entity in the IMS domain is multiple MGCFo in different geographical locations.
  • the CSAF in the IMS domain adopts the same bearer optimization strategy as the MGCF that the session has been routed, and the mobile network circuit switched CS domain uses the CAMEL mechanism to be called.
  • the call is triggered to the flowchart of the anchor with the DTF function.
  • the improvement of the present invention is mainly in the steps 2-6 and 2-10 to 2-13, and the other steps are substantially the same as those described in the background art.
  • the gsmSCF with CSAF generates a routing number IMRN pointing to an AS with DTF function in the IMS domain, so that the GMSC routes the call to the DTF according to the routing number.
  • the composition of the IMRN may be "route prefix + DTF PSI + call reference number".
  • the route prefix is used to indicate that the GMSC can be fixedly addressed to one of the MGCFs in the IMS domain
  • the DTF PSI is used to indicate that the call needs to be anchored in the IMS.
  • the call reference number is used to uniquely identify a call.
  • the gsmSCF with the CSAF can allocate the route prefix corresponding to the MGCF closest to the GMSC according to the address information of the GMSC, so that the GMSC can route the call to the MS domain. Then, the gsmSCF with the CSAF sends the IMRN to the GMSC through the CAMEL connect message.
  • the session information received by the AS having the DTF function includes the MRN session of the DTF PSI information
  • the session is anchored, that is, the B2BUA (Back-to-Back User Agent) function is triggered, and the function is terminated.
  • the session received by the AS is deleted, and then a new session for the original called information is initiated. That is, the AS having the DTF function obtains the S-CSCF information of the called user side through the Sh interface with the HSS, and then routes the session to the S- CSCF, and the session is routed by the S-CSCF to the original called side.
  • the CSRN may be configured as a "routing prefix + original called information + call reference number".
  • the routing prefix is used to indicate that the S-CSCF can be fixedly addressed to a certain MGCF, and the CSAF is allocated with the IMRN allocated in steps 2-6.
  • the same routing prefix is used to ensure that the S-CSCF can route the session back to the same MGCF to which the GMSC routes the call in steps 2-6.
  • the original called information is used to indicate the called information that the real call should be connected, call reference The number is used by the MGCF to identify which two calls (incoming call and outgoing call) are received and belong to the same call.
  • the AS with the DTF function initiates a new session for the original called information
  • the AS with the CSAF needs to perform route analysis on the original called information, and the AS with the CSAF determines that the session needs to be routed to the mobile network circuit switching.
  • the AS with the CSAF constructs the CSRN in the TEL URI format based on the original called information, and then the called information Requested-URI in the new session initiated by the AS with the DTF function for the original called information is CSRN.
  • the S-CSCF is executed.
  • the ENUM DNS conversion function if the original called number can be converted into the SIP URI format, the subsequent call routing is performed in the IMS domain. Otherwise, the S-CSCF routes the call to the BGCF of the IMS domain, and the call is finally terminated by the BGCF.
  • the GMSC is routed to the mobile network circuit switched CS domain via the MGCF, and finally the call is connected by the GMSC to the called party.
  • the DTF-enabled AS enables the B2BUA function
  • the DTF maintains the state for the session terminated in the DTF and the newly initiated session in the DTF to control the inter-domain handover that may be initiated by subsequent users.
  • the MGCF determines, according to the call reference number MGCF in the called information CSRN, the call received by the MGCF, that is, the IAM sent by the MGCF in step 2-8, and The session sent by the MGCF, that is, the IAM sent by the MGCF to the GMSC belongs to the same call in this step.
  • the MGCF controls the MGW to not perform codec conversion on the inbound and outbound sessions, that is, the IAM sent by the MGCF to the received GMSC.
  • the service can be continually connected to the voice service initiated by the MGW to the DTM bearer of the GMSC.
  • CSAF in the IMS domain uses the same bearer optimization strategy as the MGCF that the session has been routed, and the mobile network circuit switched CS domain uses signaling interception.
  • the mechanism triggers an incoming call to a flowchart with the DTF-enabled AS anchoring.
  • the improvement of the present invention is mainly in the steps 3-5 and 3-9 to 3-12, and the other steps are substantially the same as those described in the background art.
  • the SRF with CSAF generates a routing number IMRN pointing to an AS with DTF function in the IMS domain, so that the GMSC routes the call to the DTF according to the routing number.
  • the composition of the IMRN may be "route prefix + DTF PSI + call reference number".
  • the route prefix is used to indicate that the GMSC can be fixedly addressed to one of the MGCFs in the IMS domain
  • the DTF PSI is used to indicate that the call needs to be anchored in the IMS.
  • the call reference number is used to uniquely identify a call.
  • the SRF with the CSAF can allocate the route prefix corresponding to the MGCF closest to the GMSC according to the address information of the GMSC, so that the GMSC can route the call to the IMS domain. Then, the SRF with CSAF mimics the functional phase of the HLR.
  • the GMSC returns an SRI-Ack message, and the SRI-Ack message sends the IMRN as the called routing information to the GMSC.
  • the session information received by the AS with the DTF function includes the IMRN session of the DTF PSI information in step 3-9 to step 3-12
  • the session is anchored, that is, the B2BUA (back-to-back user agent) function is triggered, and the terminal is terminated.
  • the session received by the AS is deleted, and then a new session for the original called information is initiated. That is, the AS with the DTF function obtains the S-SCF information of the called user side through the Sh interface with the HSS, and then routes the session to the S. -CSCF, and the session is routed by the S-CSCF to the original called side.
  • the CSRN may be configured as a "routing prefix + original called information + call reference number".
  • the routing prefix is used to indicate that the S-CSCF can be fixedly addressed to a certain MGCF, and the CSAF allocation is the same as that in the IMRN allocated in step 6.
  • the routing prefix is used to ensure that the S-CSCF can route the session back to the same MGCF to which the GMSC routes the call in step 6.
  • the original called information is used to indicate the called information that the real call should be connected, and the call reference number is used for the MGCF. Identifies which two calls (incoming call and outgoing call) are received and belong to the same call.
  • the AS with the DTF function initiates a new session for the original called information
  • the AS with the CSAF needs to perform route analysis on the original called information, and the AS with the CSAF determines that the session needs to be routed to the mobile network circuit switching.
  • Continuation in the CS domain The AS with the CSAF constructs the CSRN in the TEL URI format based on the original called information, and then the called information Requested-URI in the new session initiated by the AS with the DTF function for the original called information is CSRN.
  • the S-CSCF performs the ENUM DNS conversion function, if the original called number can be converted into the SEP URI format. Then, the subsequent call routing is performed in the MS domain. Otherwise, the S-CSCF routes the call to the BGCF of the IMS domain, and the BGCF finally routes the call to the GMSC of the mobile network circuit-switched CS domain via the MGCF, and finally the call is made by the GMSC.
  • the DTF-enabled AS enables the B2BUA function
  • the DTF maintains the state for the session terminated in the DTF and the newly initiated session in the DTF to control the inter-domain handover that may be initiated by subsequent users.
  • the MGCF determines, according to the call reference number MGCF in the called information CSRN, that the call received by the MGCF is the IAM sent by the GMSC received by the MGCF in step 8, and is sent by the MGCF.
  • the MGCF controls the MGW to not perform codec conversion on the inbound and outbound sessions, that is, the IAM message sent by the MGCF to the received GMSC.
  • the control MGW does not convert its DTM bearer into an IP bearer, and the MGCF controls the MGW to directly use the previously received DTM bearer for the IAM message sent to the GMSC, so that the voice service initiated by the GMSC to the DTM bearer of the MGW can be losslessly It is connected to the voice service initiated by the MGW to the DTM bearer of the GMSC.
  • the CSAF in the IMS domain adopts the same bearer optimization policy as the MGCF that the session has traversed, and the MSISDN user in the IMS domain acts as the called user, CS domain.
  • a flow chart in the PSTN network that routes the call to the IMS domain based on the analysis of the called number and triggers an anchor to the AS.
  • the improvement of the present invention is mainly in the step 4-2 and the steps 4-7 to 4-9, and the other steps are basically the same as those described in the background art.
  • the MGCF converts the MSISDN into a TEL URI and sends an INVITE message to the I-CSCF.
  • the MGCF sends the INVITE message to the I-CSCF, and the called information Requested-URI is in the form of "route prefix + called information such as TEL URI + call reference number".
  • the route prefix is used to indicate that the S-CSCF can be fixed.
  • the call reference number assigned by the MGCF is used by the MGCF to identify which two calls are received, that is, the incoming call and the outgoing call belong to the same call. Further, the call reference number may also include a CS domain or a PSTN network initiated.
  • step 4-7 the AS with the CSAF performs route analysis on the called information, and when the AS with the CSAF determines that the session needs to be routed to the mobile network circuit switched CS domain, the AS with the CSAF is based on the original The information is called CSRN in the TEL URI format, and then the DTF function is triggered.
  • the composition of the CSR may be "route prefix + original called information + call reference number", where the route prefix is used to indicate that the S-CSCF can be fixedly addressed to a certain MGCF, and the AS with CSAF is assigned the same as step 4-2.
  • the original called information is used to indicate The called information that the real call should be connected, the call reference number is used by the MGCF to identify which two calls are received, that is, the incoming call and the outgoing call belong to the same call.
  • the AS with CSAF is assigned with the MGCF in the INVITE message in step 2. The same call reference number carried in.
  • the AS with DTF function anchors the session received by the AS with CSAF, which triggers the B2BUA function, terminates the session received by the AS, and then initiates a message for the original called.
  • New session called in the new session
  • the information Requested-URI is the CSRN of the AS structure with CSAF. That is, the AS having the DTF function obtains the S-CSCF information of the called user side through the Sh interface with the HSS, and then routes the session to the S-CSCF, and the session is routed to the original called side by the S-CSCF.
  • the Requested-URI is CSRN.
  • the S-CSCF cannot convert it into a SIP URI format. Therefore, the S-CSCF routes the session to the BGCF of the IMS domain, and the BGCF forwards the session to the MGCF to the mobile network circuit.
  • Exchange CS domain
  • the MGCF determines, according to the call reference number MGCF, the session that it has received, that is, the IAM message sent by the CS domain or the PSTN network received by the MGCF in step 4-1, and the sent Session is in this step
  • the IAM message sent by the MGCF to the CS domain or the PSTN network belongs to the same call.
  • the MGCF controls the MGW to perform codec conversion on the incoming and outgoing calls, that is, the MGCF controls the MGW for the received IAM message sent by the GMSC.
  • the DMG bearer is not converted into an IP bearer, and the MGCF controls the MGW to directly use the previously received DTM bearer for the IAM message sent to the GMSC, so that the voice service in the DTM bearer initiated by the CS domain or the PSTN network to the MGW can be enabled. Losslessly connected to the voice service initiated by the MGW to the DTM bearer of the CS domain or the PSTN network.
  • the DTF When the DTF-enabled AS enables the B2BUA function, the DTF maintains the state for the session terminated in the DTF and the newly initiated session in the DTF to control the inter-domain handover that may be initiated by subsequent users.
  • the technical solution of reducing the DTM bearer path to optimize the DTM bearer path based on the first core technology content provided by the present invention is further described below by taking the called side session that needs to be statically anchored in the IMS domain as an example.
  • MGCF bearer optimization strategy in which the CSAF in the IMS domain adopts the closest MGCF to the current MSC of the called user, and the CAMEL mechanism is used in the CS domain of the mobile network.
  • the flow of the incoming call is triggered to the AS with the DTF function.
  • the improvement of the present invention is mainly in the steps 2-10 to 2-13, and the other steps are basically the same as those described in the background art.
  • the session information received by the AS with the DTF function includes the IMRN session of the DTF PSI information
  • the session is anchored, that is, the B2BUA (Back-to-Back User Agent) function is triggered, and the function is terminated.
  • the session received by the AS is deleted, and then a new session for the original called information is initiated. That is, the AS having the DTF function obtains the S-CSCF information of the called user side through the Sh interface with the HSS, and then routes the session to the S- CSCF, and the session is routed by the S-CSCF to the original called side.
  • the composition of the CSRN may be "routing prefix + original called information + call reference number", where the routing prefix is used to indicate that the S-CSCF can be fixedly addressed to a certain MGCF.
  • the CSAF may first send an ATI to the HLR, query the registration status of the current mobile network circuit switched CS domain, and determine the current location information of the user according to the Location lnforaiation information in the ATI Ack message returned by the HLR, and then The CSAF allocates a route prefix that can be addressed to the nearest MGCF of the VMSC of the current mobile network circuit switched CS domain of the called subscriber. .
  • the AS with the DTF function initiates a new session for the original called information
  • the AS with the CSAF needs to perform route analysis on the original called information, and the AS with the CSAF determines that the session needs to be routed to the mobile network circuit switching.
  • the AS with the CSAF constructs the CSRN in the TEL URI format based on the original called information, and then the called information Requested-URI in the new session initiated by the AS with the DTF function for the original called information is CSRN.
  • the S-CSCF is executed.
  • the ENUM DNS conversion function if the original called number can be converted into the SIP URI format, the subsequent call routing is performed in the IMS domain. Otherwise, the S-CSCF routes the call to the BGCF of the IMS domain, and the call is finally terminated by the BGCF.
  • the GMSC is routed to the mobile network circuit switched CS domain via the MGCF, and finally the call is connected by the GMSC to the called party.
  • the S-CSCF forwards the call to the MGCF
  • the S-CSCF determines that the MGCF to be routed does not belong to the IMS domain, that is, the IMS domain to which the user belongs, according to the routing prefix of the CRSN, if the user roams, the user's home IMS domain cannot be overwritten.
  • the router needs to be routed across the IMS domain.
  • the IJS-CSCF selects the BGCF of the MS domain and routes the session to the BGCF.
  • the BGCF of the local domain routes the call to the route prefix.
  • the BGCF in the IMS domain of the user visited the subsequent BGCF addresses the MGCF closest to the current VMSC of the user according to the routing prefix, and then routes the call to the MGCF.
  • the MGCF entity also acts as a GMSC entity, and the MGCF function in the entity sends an IAM message to the internal GMSC function.
  • the DTF When the DTF-enabled AS enables the B2BUA function, the DTF maintains the state for the session that is terminated in the DTF and the newly initiated session in the DTF to control the inter-domain handover that may be initiated by subsequent users.
  • the method of the intelligent network service or other conversion technology is used to parse the MSISDN of the original called user, and then the GMSC is based on the GMSC function.
  • the parsed MSISDN sends an SRI message to the HLR.
  • the interception mechanism triggers an incoming call to a flowchart with the DTF-enabled AS anchoring.
  • the improvement of the present invention is mainly in steps 3-9 to 3-12 and steps 3-14, and the other steps are substantially the same as those described in the background art.
  • the session information received by the AS with the DTF function includes the IMRN session of the DTF PSI information in step 3-9 to step 3-12
  • the session is anchored, that is, the B2BUA (back-to-back user agent) function is triggered, and the terminal is terminated.
  • the session received by the AS is deleted, and then a new session for the original called information is initiated. That is, the AS with the DTF function obtains the S-CSCF information of the called user side through the Sh interface with the HSS, and then routes the session to the S- CSCF, and the session is routed by the S-CSCF to the original called side.
  • the CSRN may be configured as a "routing prefix + original called information + call reference number".
  • the routing prefix is used to indicate that the S-CSCF can be fixedly addressed to a certain MGCFo.
  • the CSAF may first send an ATI to the HLR before allocating the CSRN. Querying the registration status of the current mobile network circuit switched CS domain, and determining the current location information of the user according to the Location Information information in the ATI Ack message returned by the HLR, and then the CSAF allocation can be addressed to the current location of the called user.
  • the mobile network circuit switches the routing prefix of the nearest MGCF of the VMSC of the CS domain.
  • the AS with the DTF function initiates a new session for the original called information
  • the AS with the CSAF needs to perform the path analysis on the original called information, and the AS with the CSAF determines that the session needs to be routed to the mobile network circuit.
  • the AS with CSAF constructs the CSRN in the TEL URI format based on the original called information, and then the called information Requested-URI in the new session initiated by the AS with the DTF function for the original called information is CSRN.
  • the S-CSCF performs the ENUM DNS conversion function, if the original called number can be converted into a SIP URI.
  • subsequent call routing is performed in the IMS domain.
  • the S-CSCF routes the call to the BGCF of the IMS domain, and the BGCF finally routes the call to the mobile network via the MGCF.
  • Circuitry exchanges the GMSC of the CS domain, and finally the GMSC connects the call to the called party.
  • the S-CSCF forwards the call to the MGCF
  • the S-CSCF determines that the MGCF to be routed does not belong to the MS domain, that is, the IMS domain to which the user belongs, according to the routing prefix of the CRSN, if the user roams, the user's home IMS domain cannot be overwritten.
  • the S-CSCF selects the BGCF of the IMS domain to route the session to the BGCF, and the BGCF of the local domain routes the call according to the route prefix to the CS domain of the mobile network circuit that the user is currently visiting.
  • the BGCF in the IMS domain of the user visited the subsequent BGCF addresses the MGCF closest to the current VMSC of the user according to the routing prefix, and then routes the call to the MGCF.
  • the MGCF entity also acts as a GMSC entity, and the MGCF function in the entity sends an IAM message to the internal GMSC function.
  • the DTF When the DTF-enabled AS enables the B2BUA function, the DTF maintains the state for the session terminated in the DTF and the newly initiated session in the DTF to control the inter-domain handover that may be initiated by subsequent users.
  • the MSISDN of the original called user may be parsed by using a certain conversion technology, and then the called party is called based on the parsed MSISDN.
  • the GMSC function in the MGCF/GSMC entity sends an SRI message to the HLR to obtain routing information of the called user.
  • the call is also intercepted by the SRF with CSAF. If the SRF with CSAF determines that the call has been processed, the SRI that is intercepted in the column is not analyzed, and the corresponding inter-domain routing policy control processing is not performed.
  • the HLR forwards the SRI message and forwards the SRI-Ack message returned by the HLR it receives to the MGCF/GSMC entity.
  • the GMSC function in the MGCF/GSMC entity routes the call to the visited VMSC of the called user according to the received routing information of the called user in the SRI-Ack.
  • the MSISDN user in the IMS domain is the called user, CS
  • the CSAF in the IMS domain is the closest to the current VMSC of the called user.
  • a flow diagram in the domain or PSTN network that routes calls to the IMS domain based on an analysis of the called number and triggers anchoring to the AS.
  • the improvement of the present invention is mainly in steps 4-6 to 4-9, and the other steps are substantially the same as those described in the background art.
  • the session information received by the AS with the DTF function includes the IMRN session of the DTF PSI information in step 4-6 to step 4-9
  • the session is anchored, that is, the B2BUA (back-to-back user agent) function is triggered, and the terminal is terminated.
  • the session received by the AS is dropped, and then a new session is initiated for the original called information. That is, the AS with the DTF function obtains the S-CSCF information of the called user side through the Sh interface with the HSS, and then routes the session to the S. -CSCF, and the session is routed by the S-CSCF to the original called side.
  • the composition of the CSRN may be "routing prefix + original called information + call reference number", where the routing prefix is used to indicate that the S-CSCF can be fixedly addressed to a certain MGCF.
  • the CSAF may first send an ATI to the HLR, query the registration status of the current mobile network circuit switched CS domain, and determine the current location information of the user according to the Location Information information in the ATI Ack message returned by the HLR. The CSAF then allocates a route prefix that can be addressed to the nearest MGCF of the VMSC of the current mobile network circuit switched CS domain of the called subscriber.
  • the AS with the DTF function initiates a new session for the original called information
  • the AS with the CSAF needs to perform route analysis on the original called information, and the AS with the CSAF determines that the session needs to be routed to the mobile network circuit switching.
  • the AS with the CSAF constructs the CSRN in the TEL UI format based on the original called information, and then the called information Requested-URI in the new session initiated by the AS with the DTF function for the original called information is CSRN.
  • the S-CSCF performs the ENUM DNS conversion function, if the original called number can be converted into the SIP URI format. , subsequent call routing in the MS domain Otherwise, the S-CSCF routes the call to the BGCF of the IMS domain, and the BGCF finally routes the call to the GMSC of the mobile network circuit switched CS domain via the MGCF, and finally the GMSC connects the call to the called party.
  • the S-CSCF forwards the call to the MGCF
  • the S-CSCF determines that the MGCF to be routed does not belong to the IMS domain, that is, the S-domain to which the user belongs, according to the routing prefix of the CRSN, if the user roams, the user's home IMS domain cannot be overwritten.
  • the S-CSCF selects the BGCF of the IMS domain to route the session to the BGCF, and the BGCF of the local domain routes the call according to the route prefix to the CS domain of the mobile network circuit that the user is currently visiting.
  • the BGCF in the IMS domain of the user visited the subsequent BGCF addresses the MGCF closest to the current VMSC of the user according to the routing prefix, and then routes the call to the MGCF, the MGCF entity also serves as the GMSC entity, and the MGCF function in the entity is internal to The GMSC function sends an IAM message.
  • the DTF When the DTF-enabled AS enables the B2BUA function, the DTF maintains the state for the session terminated in the DTF and the newly initiated session in the DTF to control the inter-domain handover that may be initiated by subsequent users.
  • the method of the intelligent network service or other conversion technology is used to parse the MSISDN of the original called user, and then the GMSC is based on the GMSC function.
  • the parsed MSISDN sends an SRI message to the HLR.
  • the foregoing embodiments are described in terms of two different bearer optimization strategies, respectively.
  • the focus of the solution is different, and the solution side is more important than reducing the number of conversions of the voice codec to ensure the quality of the voice service, and the introduction of the static anchor scheme is eliminated.
  • Solution 2 focuses on extending the IP bearer path of the session as much as possible, reducing the DTM bearer path, improving the utilization of IP bearers, and reducing the operating cost of the network.
  • the present invention can also be used in combination with the above two technical solutions, that is, the AS with the CSAF can determine the allocation according to the operator's preference setting, the current location information of the called circuit in the CS domain of the mobile network, etc.
  • the CSRN when the CSRN is allocated.
  • the CSRN is to route the session back to the same MGCF as the incoming IMS and the call or to route the session to the MGCF that is far out of the IMS domain.
  • the MGCF needs to be modified.
  • the operator's preference setting may be: The combination of the first solution and the second solution of the present invention is
  • the AS with the CSAF determines that the Requested-URI in the received INVITE message is the IMRN
  • the subsequent call processing is performed by using the scheme 1 of the present invention, that is, the CSRN allocated by the AS with the CSAF can route the session back and the call into the IMS domain.
  • the selected MGCF when the CSAF determines that the Requested-URI in the received INVITE message is a TEL URI, then performs subsequent call processing by using the second scheme of the present invention, that is, the CSRN allocated by the AS with CSAF can route the session. To the MGCF of the IMS domain with the current VMSC of the called user.
  • the session routing path control system provided by the present invention is as shown in FIG.
  • the session routing path control system of the present invention includes: a network entity determining module, an MS intra-domain routing module, and an inter-domain routing module.
  • the network entity determining module is mainly used to determine the network entity in the IMS domain corresponding to the session.
  • the network entity determination module is located in the application server in the present invention.
  • the network entity determining module may determine the network entity in the IMS domain by using a predetermined bearer optimization policy, such as determining the IMS by using the same bearer optimization policy as the MGCF that the session has been routed, and the MGCF closest to the current MSC of the called user.
  • the network entity in the domain is implemented as described in the above method.
  • the routing module in the IMS domain is mainly used to obtain network entity information in the S domain determined by the network entity determining module, and according to the network The entity information routes the session that needs to be routed to the circuit switched domain to the IMS domain network entity.
  • the IMS intra-domain routing module can be located in the S-CSCF in the IMS domain. There are various methods for the routing module in the IMS domain to obtain network entity information in the IMS domain, as described in the foregoing method.
  • the inter-domain routing module is mainly used to obtain network entity information that needs to be routed to the circuit switched domain, and routes the route routed by the routing module in the IMS domain to a network entity such as an MSC in the circuit switched domain.
  • the inter-domain routing module is located in a network entity in the IMS domain, such as the MGCF.
  • the function of the inter-domain routing module is implemented by the IMS domain function sub-module and the circuit switched domain function sub-module.
  • the IMS domain function sub-module receives the session forwarded by the routing module in the IMS domain and routes it to the circuit switched domain function sub-module.
  • Circuit Switching Domain Function Sub-module Completes the route analysis of the called user in the circuit switched domain and routes the call to the switching center where the user is currently located according to the route analysis.
  • the second core technical content of the present invention is that when a call needs to be routed from the circuit switched domain to the IMS domain, if the application server can control the live routing path according to the predetermined routing policy, different route optimization or bearer optimization can be implemented.
  • the static anchor scheme under the call continuity topic, if the VMSC/GMSC in the CS domain can route the call to the MGCF of the IMS domain, the DTM bearer path can be shortened as much as possible, and the static anchor scheme can be reduced.
  • the impact of the introduced DTM bearer is optimized to optimize the DTM bearer path of the session.
  • the application server of the present invention is an AS with routing control function in the IMS domain, that is, an AS with CSAF, or a routing control function in the CS domain of the mobile network.
  • gsmSCF ie g smSCF with CSAF.
  • the network entity in the IMS domain is a plurality of MGCFs in different geographical locations.
  • the MGCFs set in the IMS domain and located in different geographical locations are respectively MGCF1, MGCF2, MGCF3, and MGCF4, as shown in FIG. 6.
  • the application server can determine the location information of the MSC according to the information carried by the MSC to the call trigger, that is, the current location information of the calling user. In this way, the application server can determine the information that needs to be routed to an MGCF in the IMS domain according to a predetermined policy. For example, if the application server sets the nearest routing policy, the application server determines the location closest to the MSC according to the nearest routing policy.
  • the application server determines the MGCF information closest to the VMSC in the CS domain of the mobile network, i.e., the MGCF4 information, and then provides the VMSC with the IMRN4 containing the MGCF4 route prefix as the new called information.
  • the VMSC analyzes the obtained new called information, the call can be routed to the MGCF4 according to the MGCF4 routing prefix information included in the RN4.
  • the present invention effectively shortens the distance of the DTF bearer between the CS domain and the IMS domain of the mobile network, and optimizes the DTM bearer routing.
  • the foregoing application server provides MGCF routing information to the MSC in various ways, such as being directly included by the application server.
  • the IMRN of the MGCF routing prefix is provided to the MSC as new called information.
  • the IMRN that provides the MGCF routing prefix is provided to the UE by the application server, and the UE carries the IMRN as the called information to the MSC when the call is initiated.
  • the application server When the application server provides the MGCF routing information to the MSC, it can provide routing information of the MGCF in the IMS domain that can be routed to the IMS domain, that is, the called information DTF PSI belongs to the MGCF.
  • the location information and the corresponding routing information for example, according to the MSC location information, it is determined that the MSC is away from a certain MGCF in another IMS domain.
  • the application server can also provide routing information that can be routed to other IMS domains, that is, MGCFs in the MS domain to which the called information (DTF PSI) belongs.
  • the MGCF After the mobile network circuit switched CS domain calls are routed to the MGCF in other IMS domains, the MGCF needs to call the called party because the MGCF in the other MS domain cannot determine the domain name of the called information (DTF PSI) that is not in the IMS domain.
  • the information is converted into ENUM DNS, and after converting the DTF PSI in the TEL URI format into a SIP URI, the address information of the I-CSCF in the IMS domain of the DTF PSI is determined according to the domain name information of the SIP URI, and then the call is routed to the I-CSCF. .
  • the call of the circuit switched CS domain of the mobile network may be an initial call initiated by the calling side of the CS domain in the mobile network circuit switching, or may be an initial call initiated by the called side in the CS domain of the mobile network circuit, and the corresponding MSC may be
  • the VMSC or the GMSC, and the predetermined triggering mechanism of the MSC also includes various, such as a CAMEL mechanism, a USSD mechanism, a Notify mechanism, and a signaling interception mechanism.
  • the calling subscriber's VMSC of the mobile network circuit switched CS domain triggers the call of the calling subscriber through the CAMEL mechanism to the mobile network circuit-switched CS domain gsmSCF in the CS domain, which triggers the mobile network circuit-switched CS.
  • Domain call side CAMEL subscription information '
  • step 1-3 the gsmSCF with CSAF learns that the CAMEL interaction is initiated by the calling side user through the detected detection point in the received CAMEL message IDP (Initial Detected Point).
  • IDP Initial Detected Point
  • the interaction of the call, and according to the MSC address information in the IDP message, can determine the location information of the currently located VMSC of the mobile network circuit switched CS domain calling user, and then according to the network data configuration information, such as different MGCF and VMSC
  • the geographical location information determines that the VMSC where the calling user is currently located is closest to MGCF4.
  • the allocated IMRN should include the routing information of the MGCF4, so that the VMSC can route the call to the MGCF4 according to the IMRN.
  • the IMRN including the MGCF4 routing information is referred to as IMRN4
  • the configuration of the IMRN4 may be: MGCF4 routing prefix + DTF PSI + calling reference number.
  • the present invention does not limit the location of the MGCF4 routing information in the IMRN.
  • the gsmSCF with CSAF sends the IMR 4 as the new called message to the mobile network circuit through the CAMEL connect operation to exchange the VMSC where the calling user is currently located in the CS domain.
  • step 1-4 when the VMSC analyzes the received new called information, the VMSC can route the call to the nearest MGCF 4 according to the MGCF4 routing information contained in the IMRN4. Thereby, the DTM bearer bypass path introduced by the call control scheme of the static anchor point is reduced.
  • the VMSC When the configuration of the IMRN is "MGCF Routing Prefix + DTF PSI + Call Reference Number", the VMSC is enabled to receive the IMRN in the CAMEL connect operation, and when the received new called information is analyzed, the information contained in the IMRN is included.
  • the analysis of the routing information of the MGCF can route the call to the corresponding MGCF, and the MGCF can remove the routing information of the MGCF included in the IMRN, such as deducting the IMRN routing prefix, and restoring the IMRN to the "DTF PSI+call reference number" manner.
  • the call in the subsequent process will be processed according to the description in the prior art. Steps 1-5 to 1-7 in FIG. 1 of the background art do not affect the related processing of other entities.
  • the GMSC will receive the call from the calling side using the CAMEL mechanism.
  • the DRF-enabled gsmSCF generates a routing number IMRN (IMS Routing Number) that points to an AS with DTF functionality in the IMS domain, such that the GMSC routes the call to the DTF based on the routing number.
  • IMRN IMS Routing Number
  • the gsmSCF with the DRF function allocates the IMRN, it needs to be allocated according to the current GMSC location information of the gsmSCF with DRF function in the mobile network circuit switched CS domain, such as the gsmSCF with DR function.
  • the trigger detection point in the CAMEL message IDP received in 2-3 is DP12.
  • the current CAMEL interaction is an interaction of the called side user, and the mobile network circuit switched CS domain can be determined according to the MSC address information in the IMP message.
  • the location information of the GMSC in the called subscriber's home network is determined, and then the GMSC in the called subscriber's home network is determined to be closest to the MGCF4.
  • the allocated RN should include the routing information of the MGCF4, so that the GMSC can route the call to the MGCF4 according to the IMRN.
  • the IMRN including the MGCF4 routing information is referred to as IMRN4
  • the configuration of the IMRN4 may be: MGCF4 route prefix + DTF PSI + call reference number.
  • the present invention does not limit the location of MGCF4 routing information in the IMRN.
  • the gsmSCF with the DRF function sends the IMRN4 as the new called information to the GMSC to which the called user belongs in the mobile network circuit switched CS field through the CAMEL connect operation.
  • step 2-7 when the GMSC analyzes the received new called information, the GMSC can route the call to the closest MGCF4 according to the MGCF4 routing information contained in the IMRN4. Thereby, the DTM bearer bypass path introduced by the call control scheme of the static anchor point is reduced.
  • the second core technical content of the present invention can also be applied to the USSD mechanism, the Notify mechanism, the signaling interception mechanism, etc., and the core technical contents of the implementation are the same, except that the specific signaling name and the network entity are slightly different. , will not be described in detail here.
  • the routing path control system provided by the present invention is as shown in FIG.
  • the routing path control system includes: an IMS domain network entity determining module and a routing module.
  • the IMS domain network entity determining module For a call that needs to be routed from the circuit switched domain to the IMS domain, the IMS domain network entity determining module determines network entity information in the corresponding IMS domain to which the call is routed according to a predetermined policy, the IMS domain
  • the network entity can be: MGCF.
  • the IMS domain network entity determining module may determine the IMS domain network entity information according to the initial call initiated by the calling side in the circuit switched domain, the initial call initiated by the called side in the circuit switched domain, and different call triggering modes, respectively. Further, the IMS domain network entity determining module provides the determined IMS domain network entity information to the routing module. The specific process is as described in the above method and will not be described in detail herein.
  • the MS domain network entity determining module may be located in an AS of the IMS domain, such as an AS with CSAF in the IMS domain, or in an entity in the circuit switched domain, such as the gsmSCF of the CS circuit domain of the mobile network.
  • the routing module routes the call to the corresponding entity in the IMS domain, such as the corresponding MGCF, according to the IMS domain network entity information provided by the IMS domain network entity determining module.
  • the IMS domain network entity determining module provides the IMS domain network entity information to the routing module by various methods, such as operating the called information parameter through the CAMEL connect, or the MSRN parameter in the SRI-Ack message to carry the IMS domain network entity information. The specific process is as described in the above method and will not be described in detail herein.
  • the routing module can be located in an entity in the circuit switched domain, such as a switching center such as a VMSC or GMSC located in the circuit switched CS domain of the mobile network. '

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Description

会话路由路径控制方法和系统
技术领域
本发明涉及网络通讯技术领域， 具体涉及会话路由路径控制方法和系统。
发明背景
目前 3GPP( 3rd Generation Partnership Project,第三代移动通信标准化伙伴项目）提出了一种 IMS
( IP多媒体子系统）控制的静态锚点（IMS control static anchoring)的呼叫控制方案， 以解决在两个 域， 如 CS (电路交换）域和 IMS域， 之间进行切换的问题。 该方案的核心技术内容是， 对于无论 从 CS域或是 IMS域发起的呼叫 /会话， 都将该呼叫 /会话触发至 IMS域中的一个 AS (Application Server, 应用服务器）， 由该 AS对呼叫 /会话进行锚定控制 （Anchoring control)。 这样， 后续无论发 生 CS域至 IMS域的域间切换或是发生 IMS域至 CS域的域间切换， 都由该 AS对锚定的呼叫 /会话 进行后续切换控制处理。
由于 IMS中会话控制方式本身就可以很方便的在呼叫路径中插入一个锚点 AS对会话进行控制， 即通过定义 iFC使得会话触发至 AS。 而对于 CS域的呼叫控制方式本身不太容易在呼叫路径中插入 一个锚点 AS, 因此针对 CS域发起的呼叫触发至锚点 AS的过程， 3GPP规范目前描述了多种方案： 对于主叫侧为 CS域时发起的初始呼叫， 即对于主叫侧 VMSC ( Visited Mobile Switch Center拜访移 动交换中心） 在接收到 UE 的呼叫建立消息后发起的呼叫， 可以有网络侧路由控制即使用 CA^EL ( Customised Application for Mobile network Enhanced Logic , 移动网络增强逻辑用户应用）方案， 和 终端侧路由控制即使用 USSD (Unstructured Supplementary Service Data, 无结构化补充业务数据） 和 Notify (通知） 方案， 两种控制模式将呼叫路由至锚点 AS。 对于被叫侧为 CS域时发起的初始呼 叫，即被叫归属网络的 GMSC在接收到来自于主叫侧的呼叫后，根据 GMSC对被叫信息分析后发起 的呼叫， 可以使用 CAMEL方案和信令拦截方案将呼叫路由至锚点 AS。
这种将初始呼叫路由至锚点 AS的功能叫做 CSAF ( Circuit Switched Adaptation Function电路域 适配功能）， 对于 CS域， 具有 CSAF的实体可以为 gsmSCF, 对于 IMS域， 具有 CSAF的实体可以 为一个 AS。 CS域中的路由决策实体 gsmSCF可以同 IMS域中的路由决策实体 AS位于同一个物理 实体中。
上述 AS的锚定控制功能用于实现域间切换的主要原理是， 在呼叫初始建立时， 如 UE (A) 发 起针对 UE (B ) 的呼叫， 通过具有 CSAF的 gsmSCF或 AS在主叫侧 UE (A) 的呼叫路径中插入一 个锚点 AS , 该 AS启用 B2BUA功能用以将主叫侧的呼叫分为 AS终止段和 AS发起段两段。 AS终 止段即为 UE (A) -AS之间的呼叫段， AS发起段即为 AS—UE (B ) 之间的呼叫段。 后续在呼叫 的过程中， UE ( A' )检测到域间切换条件满足时，希望将当前进行的呼叫从 UE ( A)切换到 UE (Α' ) 上进行后续的呼叫控制， 此时 UE (Α' ) 则针对当前的呼叫进行锚定控制的 AS发起一个新的呼叫， AS在接收到该呼叫后， 判断出需要进行域间切换时， 则 AS将 UE (Α' )新发起的呼叫与 AS发起段 接续， 然后释放掉 AS终止段的呼叫， 这样， 在锚点 AS的控制下， 使得 UE (Α' ) 并同 UE (B )进 行了呼叫的接续， 释放掉先前的 UE (A) —AS之间的呼叫段， 完成了 UE (A )到 UE (Α' )之间的 切换。 这种将呼叫进行锚定控制， 并在域间切换发生时进行切换处理的功能叫做 DTF ( Domain Transfer Function域间转移功能） 功能， 在静态锚点方案下， 具有 DTF功能的实体为 IMS域中的一 个 AS。
具有 CSAF的路由决策点 gsmSCF或 AS可以同具有 DTF功能的 AS位于同一个物理实体中。 这里， UE (A )可以是 CS域的终端， UE (Α' )可以是 IMS域的终端，通过 UE (A)到 UE (Α' ) 的呼叫切换， 实现了用户 Α的同一个呼叫从 CS域到 IMS域之间的呼叫连续性。
同样的， 在呼叫初始建立时， 可同样在主叫侧 UE (B ) 的呼叫路径中插入一个锚点 AS, 用以 实现后续被叫侧的域间切换的呼叫控制。
附图 1为 CS域的用户作为主叫发起呼叫时， 网络侧路由控制模式下， 即 CS域中使用 CAMEL 机制将发起的呼叫触发至 AS进行锚点的流程图。
图 1中， 在步骤 1-1、 注册到 VMSC ( Visited Mobile Switch Center拜访移动交换中心） 的 UE发起 呼叫。
到步骤 1-2、 VMSC根据主叫侧的 CAMEL签约信息将呼叫触发到具有 CSAF的 gsmSCF中。
到步骤 1-3、 具有 CSAF的 gsmSCF生成一个指向 IMS域中的具有 DTF功能的一个 AS的路由号码 IMRN (IMS Routing Number) , 使得 VMSC根据该路由号码将呼叫路由至该 DTF上。 具有 CSAF的 gsmSCF可通过在 DTF的标识信息 DTF PSI (DTF Public Service Identities DTF公共业务标识） 后追加 呼叫参考号等方法来构造 IMRN, 然后具有 CSAF的 gsmSCF通过 CAMEL connect消息将 IMRN下发给 VMSCo
到步骤 1-4、 VMSC根据 IMRN将呼叫路由至主叫用户归属的 IMS网络中的 MGCF (媒体网关控制 功能） 。
到步骤 1-5、 MGCF判断出 IAM消息中的被叫信息为指向具有 DTF功能的 AS的 IMRN,则向 I-CSCF 发送 INVITE (邀请）消息，该消息中的被叫信息 Requested-URI为 IMRN的 TEL URI ( describes resources identified by telephone numbers, 使用电话号码描述的资源定位标识） 格式。
到步骤 1-6、 I-CSCF根据 Requested-URI向 HSS查询路由信息， 获取同该 IMRN相关联的 AS地址信 息， 即具有 DTF功能的 AS地址信息， 然后 I-CSCF向具有 DTF功能的 AS转发 INVITE消息。 这里， 为 了支持 HSS能够根据包含 DTF PSI信息的 IMRN返回在对应的具有 DTF功能的 AS信息， 在 HSS中需要 配置 DTF PSI数据同具有该 DTF功能的 AS地址信息的对应关系。
这里， 在步骤 1-6中， I-CSCF根据 Requested-URI向 HSS査询路由信息时， HSS也可以根据该 Requested-URI包含 DTF PSI信息， 则为该 DTF PSI分配一个 S-CSCF, 并向 I-CSCF返回分配的 S-CSCF 地址， 然后 I-CSCF向该 S-CSCF转发 INVITE消息， 由 S-CSCF根据 iFC将该 INVITE触发至具有 DTF功 能的 AS上。
到步骤 1-7、具有 DTF功能的 AS接收到的被叫信息包含 DTF PSI信息的 IMRN的会话后，对会活进 行锚定控制， 即触发 B2BUA (背靠背用户代理）功能， 终止掉 AS接收到会话， 然后发起一个针对原 被叫信息的新会话，即具有 DTF功能的 AS通过同 HSS的 Sh接口获得主叫用户侧的 S-CSCF信息，然后， 将会话路由至 S-CSCF, 并由该 S-CSCF将会话路由至原被叫侧。 这里， 在 S-CSCF将呼叫路由至原被叫侧的过程中， 当原被叫信息为 TEL URI格式时， S-CSCF执 行 ENUM DNS ( E.164 Number Domain Name System E.164域名转换系统） 转换功能， 如果能够将原 被叫号码转换成 SIP URI格式，则后续的呼叫路由在 S域中进行，否贝 1」， S-CSCF将呼叫路由至本 IMS 域的 BGCF (Breakout Gateway Control Function边界网关控制功能）， 由 BGCF将呼叫最终经由 MGCF 路由至 PSTN (公共电话交换网） 或 CS域， 最后由 PSTN或 CS域将呼叫接续至被叫。 在具有 DTF功能 的 AS启用 B2BUA功能时，对于在 DTF终止的会话和在 DTF新发起的会话， DTF均要维护其呼叫状态， 以对后续用户可能发起的域间切换进行控制。
由于主叫用户拜访地的 CS域不一定支持 CAMEL, 因此需要考虑到其他替代方式将呼叫路由至 AS, 目前 3GPP的规范中提供了终端侧路由控制模式下的基于 USSD (Unstructured Supplementary Service Data非结构化补充数据业务） 和基于 Notify (通知） 的两种机制。 其中， USSD机制应用于 UE未注册到 IMS域、 UE在向 VMSC发起呼叫时， 呼叫信令中的被叫地址信息携带的是指向具有 DTF功能的 AS的 DTF PSL 从而 VMSC经由 MGCF将呼叫路由至 IMS域中具有 DTF功能的 AS。 而真实的被叫信息，如 UE (B )的号码信息， 是通过 UE向具有 CSAF的 gsmSCF (Global System for Mobile communications-Service Control Function, gsm业务控制功能） 发送的 USSD信令中携带， 这 样， 在具有 CSAF的 gsmSCF接收到 USSD信令后， 与具有 DTF功能的 AS进行交互， 通知 DTF 其当前接收到的会话的真实被叫信息， 即 USSD信令中携带 UE (B ) 的号码信息， 从而具有 DTF 功能的 AS对接收到的 UE发起的呼叫进行锚定， 即 AS启动 B2BUA功能， 终止掉 AS接收到会话， 然后发起一个针对原被叫信息的新会话，这里的原被叫信息从具有 CSAF的 gsmSCF接收到的 USSD 信令中获得。 后续处理如图 1的步骤 7所述， 根据 AS发起的新会话中的原被叫信息将会话路由至 被叫用户后接续。 Notify机制应用于 UE已经注册到 IMS域、 UE在向 VMSC发起呼叫时， 呼叫信 令中的被叫地址信息携带的时指向具有 DTF功能的 AS的 DTF PSI,从而 VMSC经由 MGCF将呼叫 路由至 IMS域中具有 DTF功能的 AS。 而真实的被叫信息， 如 UE (B ) 的号码信息， 是通过当前注 册到 IMS域的 UE向具有 CSAF的 AS发送的 SIP Notify信令中携带， 这样， 在具有 CSAF的 AS接 收到 SEP Notify信令后， 与具有 DTF功能的 AS进行交互， 通知 DTF其当前接收到的会话的真实被 叫信息， 即 SIP Notify信令中携带 UE (B ) 的号码信息， 从而具有 DTF功能的 AS对接收到的 UE 发起的呼叫进行锚定， 即 AS启动 B2BUA功能， 终止掉 AS接收到会话， 然后发起一个针对原被叫 信息的新会话，这里的原被叫信息从具有 CSAF的 AS接收到的 SIP Notify信令中获得。后续处理如 图 1的步骤 7所述， 根据 AS发起的新会话中的原被叫信息将会话路由至被叫用户后接续。
如前分析，对于被叫侧为 CS域时发起的初始呼叫， 即被叫归属网络的 GMSC在接收到来自于 主叫侧的呼叫后， 根据 GMSC对被叫信息分析后发起的呼叫， 可以使用 CAMEL方案和信令拦截方 案将呼叫路由至锚点 AS。 其中 CAMEL方案适用于 GMSC支持 CAMEL能力的情况下， 信令拦截 方案适用于 GMSC不能支持 CAMEL能力的情况下。附图 2为 CS域的用户做被叫时， CS域中使用 CAMEL机制将接收到来自于主叫侧的呼叫触发至锚点 AS进行锚定的流程图。
在步骤 2-1、 当呼叫中被叫信息的 MSISDN属于 CS域时， 对于在 CS域或是 PSTN发起的呼叫， 在 进行被叫路由时将呼叫路由至 GMSC。 到步骤 2-2、 GMSC在接收到来自于主叫侧的呼叫后， 对被叫信息进行分析， 然后 GMSC向 HLR 发送 SRI消息以获得被叫用户的路由信息， 由于该 GMSC支持 CAMEL能力， 因此 GMSC向 HLR发送 SRI消息中携带相应的参数指示 GMSC的 CAMEL支持信息。 HLR返回指示用户为 CS- S用户的被叫 侧 CAMEL签约信息 T-CSI。
到步骤 2-3、 GMSC根据接收到的 T-CSI触发 CAMEL业务，向具有 CSAF的 gsmSCF发送 IDP ( Intitial
Detect Point, 初始检测点） 消息， 请求 CSAF的路由指示。
到步骤 2-4、 具有 CSAF的 gsmSCF从 HSS获得用户 IMS域当前的数据和状态。
到步骤 2-5、 具有 CSAF的 gsmSCF从 HLR获得用户 CS域当前的数据和状态。
到步骤 2-6、 具有 CSAF的 gsmSCF生成一个指向 IMS域中的具有 DTF功能的一个 AS的路由号码 IMRN (IMS Routing Number) , 使得 GMSC根据该路由号码将呼叫路由至该 DTF上。 具有 CSAF的 gsmSCF可通过在 DTF的标识信息 DTF PSI (DTF Public Service Identities DTF公共业务标识） 后追加 呼叫参考号等方法来构造 MRN， 然后具有 CSAF的 gsmSCF通过 CAMEL connect消息将 IMRN下发给 GMSC：。
到步骤 2-7、 GMSC根据 IMRN将呼叫路由至被叫用户归属的 IMS网络中的 MGCF。
到步骤 2-8、 同步骤 1-5。 到步骤 2-9、 同步骤 1-6。
到步骤 2-10〜步骤 2-13、 具有 DTF功能的 AS接收到的被叫信息包含 DTF PSI信息的 IMRN的会话 后， 对会话进行锚定控制， 即触发 B2BUA (背靠背用户代理）功能， 终止掉 AS接收到的会话， 然后 发起一个针对原被叫信息的新会话， 即具有 DTF功能的 AS通过同 HSS的 Sh接口获得被叫用户侧的 S-CSCF信息， 然后， 将会话路由至 S-CSCF, 并由该 S-CSCF将会话路由至原被叫侧。
这里， 具有 DTF功能的 AS发起一个针对原被叫信息的新会话时， 需要由具有 CSAF的 AS对原被 叫信息进行路由分析， 在具有 CSAF的 AS判断出需要将会话路由至 CS域中进行接续时， 具有 CSAF 的 AS基于原被叫信息构造 TEL URI格式的 CSRN(CS Routing Number CS域路由号码），然后具有 DTF 功能的 AS发起的针对原被叫信息的新会话中的被叫信息 Requested-URI为 CSRN。
这里， 在 S-CSCF将呼叫路由至原被叫侧的过程中， 当原被叫信息为 TEL URI格式时， S-CSCF执 行 ENUM DNS (E.164 Number Domain Name System E.164域名转换系统）转换功能， 如果能够将原 被叫号码转换成 SIP URI格式，则后续的呼叫路由在 IMS域中进行，否则， S-CSCF将呼叫路由至本 S 域的 BGCF (Breakout Gateway Control Function边界网关控制功能）， 由 BGCF将呼叫最终经由 MGCF 路由至 CS域的 GMSC, 最后由 GMSC将呼叫接续至被叫。 在具有 DTF功能的 AS启用 B2BUA功能时， 对于在 DTF终止的会话和在 DTF新发起的会话， DTF均对其维护状态， 以对后续用户可能发起的域间 切换进行控制。
到步骤 2-14、 GMSC接收到 MGCF的入局呼叫 IAM消息后，从中解析出原被叫用户的 MSISDN (使 用 CAMEL业务的方式或是其他的转换技术） ， 然后基于解析出的 MSISDN对被叫信息进行分析后， GMSC向 HLR发送 SRI (Sending Routing info, 发送路由信息） 消息以获得被叫用户的路由信息， 由 于该 GMSC支持 CAMEL能力， 因此 GMSC向 HLR发送 SRI消息中携带相应的参数指示 GMSC的 CAMEL支持信息。 HLR返回指示用户为 CS-IMS用户的被叫侧 CAMEL签约信息 T-CSI。 到步骤 2-15、 同步骤 2-3。
到步骤 2-16、 具有 CSAF的 gsmSCF判断出具有 DTF功能的 AS已经对该呼叫进行了锚点控制， 则 不再分配 IMRN, 直接向 GMSC下发 continue消息， GMSC接收到 continue消息后继续后续的呼叫， 即 GMSC向 HLR发送 SRI消息以获得被叫用户的路由信息 （GMSC在本次发送的 SRI消息中携带抑止 T-CSI参数） ， 然后 GMSC根据 HLR返回的被叫用户的路由信息将呼叫路由至被叫用户的拜访 VMSC 后接续。
附图 3为 CS域的用户做被叫时， CS域中使用信令拦截机制将接收到来自于主叫侧的呼叫触 发至錨点 AS进行锚定的流程图。
在步骤 3-1、 同步骤 2-1。
到步骤 3-2、 GMSC在接收到来自于主叫侧的呼叫后， 对被叫信息迸行分析， 然后 GMSC向 HLR 发送 SRI消息以获得被叫用户的路由信息， 由于该 GMSC不支持 CAMEL能力， 因此 GMSC向 HLR发 送 SRI消息中不会携带相应的参数指示 GMSC的 CAMEL支持信息。 因此 HLR不会向 GMSC返回指示 用户为 CS-IMS用户的被叫侧 CAMEL签约信息 T-CSI。 而是直接向返回被叫的路由信息， 从而无法将 呼叫锚定在 IMS域中具有 DTF功能的 AS了。 因此为了使得在 GMSC从 HLR中取的被叫的路由信息之 前能够将呼叫触发至 IMS域中具有 DTF功能的 AS进行呼叫锚定， 因此在 GMSC和 HLR之间插入信令 拦截实体 SRF (Signalling Relay Function信令转发功能） ， 该 SRF具有 CSAF, 拦截 GMSC向 HLR发送 的 SRI消息并对该消息进行分析后， 执行相应的域间路由策略控制处理。
到步骤 3-3、 具有 CSAF的 SRF从 HSS获得用户 IMS域当前的数据和状态。
到步骤 3-4、 具有 CSAF的 SRF从 HLR获得用户 CS域当前的数据和状态。
到步骤 3-5、 具有 CSAF的 SRF生成一个指向 IMS域中的具有 DTF功能的一个 AS的路由号码 IMRN
(IMS Routing Number) ， 使得 MSC根据该路由号码将呼叫路由至该 DTF上。 具有 CSAF的 gsmSCF 可通过在 DTF的标识信息 DTF PSI (DTF Public Service Identities DTF公共业务标识）后追加呼叫参考 号等方法来构造 IMRN，然后具有 CSAF的 SRF模仿 HLR的功能向 GMSC返回 SRI-Ack消息，该 SRI-Ack 消息中将 IMRN作为被叫路由信息发送给 GMSC。
到步骤 3-6、 同步骤 2-7。 到步骤 3-7、 同步骤 1-5。 到步骤 3-8、 同步骤 1-6。 到步骤 3-9〜步骤 3-12、 同步骤 2-10〜步骤 2-13。
到步骤 3-13、 GMSC接收到 MGCF的入局呼叫 IAM消息后， 使用某种转换技术从中解析出原被叫 用户的 MSISDN, 然后基于解析出的 MSISDN对被叫信息进行分析后， GMSC向 HLR发送 SRI消息以 获得被叫用户的路由信息。该呼叫同样被具有 CSAF的 SRF拦截下来， 具有 CSAF的 SRF判断出已经对 本次呼叫进行了处理， 则不对该拦截下来的 SRI进行分析， 不执行相应的域间路由策略控制处理， 直 接向 HLR转发该 SW消.息， 并将接收到的 HLR返回的 SRI-Ack消息转发至 GMSC。 然后 GMSC根据接 收到的 SRI-Ack中的被叫用户的路由信息将呼叫路由至被叫用户的拜访 VMSC后接续。
' 另外， 由于运营商在进行号码分配时， 可以为 IMS域的用户分配相应的 MSISDN号码， 用以 实现 CS域或 PSTN用户发起的对 IMS域用户的呼叫。 因此， 当 CS域或 PSTN中的用户呼叫 IMS 域中的 MSISDN用户时， 同样需要将 CS域或 PSTN用户发起的呼叫路由至被叫用户归属 IMS域中 的具有 DTF功能的 AS进行呼叫的锚定， 并由 AS对后续用户可能发起的域间切换进行控制。 到步骤 3-14、 GMSC接收到 MGCF的入局呼叫 IAM消息后， 可使用某种转换技术从中解析出 原被叫用户的 MSISDN, 然后， 基于解析出的 MSISDN对被叫信息进行分析后， GMSC向 HLR发 送 SRI消息以获得被叫用户的路由信息。 该呼叫同样被具有 CSAF的 SRF拦截下来， 具有 CSAF的 SRF判断出已经对本次呼叫进行了处理， 则不对该拦截下来的 SRI进行分析， 不执行相应的域间路 由策略控制处理， 直接向 HLR转发该 SRI消息， 并将其接收到的 HLR返回的 SRI-Ack消息转发至 GMSC。GMSC根据接收到的 SRI-Ack中的被叫用户的路由信息将呼叫路由至被叫用户的拜访 VMSC 后接续。
附图 4为 CS域或 PSTN的用户做主叫用户， IMS域中的 MSISDN用户做被叫用户时， CS域 或 PSTN网络根据对被叫号码的分析将呼叫路由至 IMS域并触发至锚点 AS进行锚定的流程图。
在步骤 4-1、 由于被叫用户的 MSISDN属于 S域， 则发起呼叫的 CS域或是 PSTN网络将呼叫路由 至被叫用户归属 IMS域中的 MGCF。
到步骤 4-2、 MGCF将 MSISDN转换成 TELURI, 并向 I-CSCF发送 INVITE消息， 该消息中的被叫 信息 Requested-U I为被叫 MSISDN的 TEL URI格式。
到步骤 4-3、 I-CSCF根据 Requested-URI向 HSS查询路由信息， 获取该用户在 IMS域中注册的
S-CSCF地址信息， 并且将会话路由至相应的 S-CSCF, 如果当前用户未注册到 IMS域中， 贝 Ijl-CSCF 将会话路由至一个为未注册用户临时分配的一个 S-CSCF中。
到步骤 4-4、 S-CSCF根据 iFC (initial Filter Criteria初始过滤准则） 将会话触发到一个具有 CSAF 的 AS中。
到步骤 4-5、 具有 CSAF的 AS从 HSS获得用户当前 IMS域的注册状态和数据。
到步骤 4-6、 具有 CSAF的 AS从 HLR获得用户当前 CS域的注册状态和数据。
到步骤 4-7、 具有 CSAF的 AS通过对被叫信息进行路由分析， 在具有 CSAF的 AS判断出需要将会 话路由至 CS域中进行接续时，具有 CSAF的 AS基于原被叫信息构造 TEL URI格式的 CSRN(CS Routing Number CS域路由号码） ， 然后触发 DTF功能。
到步骤 4-8〜步骤 4-9、具有 DTF功能的 AS对具有 CSAF的 AS接收到的会话进行锚定控制， 即触发
B2BUA (背靠背用户代理）功能，终止掉 AS接收到的会话，然后发起一个针对原被叫信息的新会活， 该新会话中的被叫信息 Requested-URI为具有 CSAF的 AS构造的 CSRN。 即具有 DTF功能的 AS通过同 HSS的 Sh接口获得被叫用户侧的 S-CSCF信息， 然后， 将会话路由至 S-CSCF, 并由该 S-CSCF将会话 路由至原被叫侧。
这里， 在 S-CSCF将会话路由至原被叫侧的过程中， 由于具有 DTF功能的 AS新发起的会话中的
Requested-URI为 CSRN, S-CSCF经过 E UM DNS转换功能后不能将其转换成 SIP URI格式， 因此 S-CSCF将会话路由至本 IMS域的 BGCF, 由 BGCF将会话最终经由 MGCF路由至 CS域的 GMSC。
在具有 DTF功能的 AS启用 B2BUA功能时， 对于在 DTF终止的会话和在 DTF新发起的会话， DTF 均对其维护状态， 以对后续用户可能发起的域间切换进行控制。
到步骤 4-10、 GMSC接收到 MGCF的入局呼叫 IAM消息后，从中解析出原被叫用户的 MSISDN (使 用 CAMEL业务的方式或是其他的转换技术） ， 然后基于解析出的 MSISDN对被叫信息进行分析后， GMSC向 HLR发送 SRI消息以获得被叫用户的路由信息， 由于该 GMSC支持 CAMEL能力， 因此 GMSC 向 HLR发送 SRI消息中携带相应的参数指示 GMSC的 CAMEL支持信息。 HLR返回指示用户为 CS- S 用户的被叫侧 CAMEL签约信息 T-CSI。
到步骤 4-Π、 同步骤 2-3。
到步骤 4-12、 具有 CSAF的 gsmSCF判断出具有 DTF功能的 AS已经对该呼叫进行了锚定控制， 则 不再分配 IMRN, 直接向 GMSC下发 continue消息， GMSC接收到 continue消息后继续后续的呼叫， 即 GMSC向 HLR发送 SRI消息以获得被叫用户的路由信息 （GMSC在本次发送的 SRI消息中携带抑止 T-CSI参数） ， 然后 GMSC根据 HLR返回的被叫用户的路由信息将呼叫路由至被叫用户的拜访 VMSC 后接续。
目前在呼叫连续性课题中提出的由 IMS控制的静态锚点（IMS control static anchoring)的呼叫控 制方案中，对于主叫侧，当呼叫在 CS域中发起，则需要将发起的呼叫从 CS域中主叫拜访地的 VMSC 路由至主叫归属 IMS域中的具有 DTF功能的 AS, 由该 AS进行呼叫的锚定并进行后续可能的域间 切换控制。当具有 DTF功能的 AS对呼叫进行锚定之后，具有 CSAF的 AS则对原主叫拜访 CS域发 起的呼叫中真实的原被叫信息进行路由分析， 当具有 CSAF的 AS判断出原呼叫需要路由回 CS域， 则根据原被叫信息产生 CSRN, 然后触发 DTF功能， 具有 DTF功能的 AS根据 CSRN将呼叫路由回 被叫归属的 CS域。 这样， 对于主叫侧为 CS域时发起的初始呼叫的整个呼叫路径为主叫拜访地的 CS域- >主叫归属的 IMS域- >被叫归属的 CS域,从而呼叫路径中承载的建立的方式是 DTM承载- >IP 承载- >DTM承载。
同样的， 对于被叫侧， 当呼叫需要在 CS域中终结， 则需要将被叫归属 CS域中的 GMSC接收 到的呼叫路由至被叫归属 IMS域中的具有 DTF功能的 AS, 由该 AS进行呼叫的锚定并进行后续可 能的域间切换控制。 当具有 DTF功能的 AS对呼叫进行锚定之后， 具有 CSAF的 AS则对原被叫归 属 CS域发起的呼叫中真实的原被叫信息进行路由决策，当具有 CSAF的 AS决定出原呼叫需要路由 回 CS域， 则根据原被叫信息产生 CSRN, 然后触发 DTF功能具有 DTF功能的 AS根据 CSRN将呼 叫路由回被叫拜访的 CS域。这样， 对于被叫侧为 CS域时发起的初始呼叫的整个呼叫路径为被叫归 属的 CS域- >被叫归属的 IMS域- >被叫拜访的 CS域， 从而呼叫路径中承载的建立的方式是 DTM承 载- >IP承载- >DTM承载。
据上分析， 原本 CS域中的主叫用户 A呼叫 CS域中的被叫用户 B的过程可以简洁地表示为： A (主叫拜访 CS域） -> B (被叫归属 CS域） ->B (被叫拜访 CS域）， 其呼叫路径中承载的建立方式 为： DTM承载- >DTM承载。 在引入静态锚点方案后， 如果仅需要对主叫侧进行锚定时， 则呼叫过 程改变为： A (主叫拜访 CS域) ->A (主叫归属 IMS域) ->B (被叫归属 CS域)- >B (被叫拜访 CS域)，从而 呼叫路径中承载的建立方式改变为： DTM承载- >IP 7?X¾->DTM承载； 如果仅需要对被叫侧进行锚 定时， 则呼叫过程改变为： A (主叫拜访 CS域) ->B (被叫归属 CS域) ->B (被叫归属 IMS域) ->B (被叫拜 访 CS域)， 从而呼叫路径中承载的建立方式改变为： DTM承载- >IP承载- >DTM承载； 如果需要对 主被叫侧都进行锚定时， 则呼叫过程改变为： A (主叫拜访 CS域) ->A (主叫归属 IMS域) ->B (被叫归属 CS域) ->B (被叫归属 IMS域) ->B (被叫拜访 CS域)，从而呼叫路径中承载的建立方式改变为： DTM承 载- >IP承载- >DTM承载- >DTM承载- >IP承载- >DTM承载。
这样， 对于 CS域- >CS域的呼叫， 由于静态锚点方案的引入， 导致在单纯的 DTM承载路由中 插入了一段或多段 IP承载路由。在 DTM承载转换成 IP承载时， 需要进行语音编解码的转换， 由于 语音编解码的转换会降低语音业务的质量， 因此静态锚点方案引入的多次语音编解码转换会严重影 响原有的语音业务质量。
另外， 对于 CS域- >CS域的呼叫， 由于静态锚点方案的引入， 导致在单纯的 DTM承载路由中 插入了一段或多段 IP承载路由， 由于 IP承载能够有效地利用网络资源， 因此可进一步对会话的路 由路径进行优化， 尽可能地延长引入的 DP承载路径， 减少 DTM承载路径， 以达到降低网络运营成 本的目的。
还有， 当呼叫在 CS域中发起， 则需要将发起的呼叫从 CS域中主叫拜访地的 VMSC路由至主 叫归属 IMS域中的具有 DTF功能的 AS, 由该 AS进行呼叫的锚定并进行后续可能的域间切换控制， 这里，为了实现将 CS域的呼叫路由至 IMS域中的具有 DTF功能的 AS,需要在主叫拜访地的 VMSC 和主叫归属 MS域中 MGCF控制下的 MGW之间建立了一段 DTM承载， 这段建立的 DTM承载是 由于为了实现静态锚点的呼叫控制方案才引入的， 因此产生了 DTM承载的路由迂回。 同样的， 当 呼叫在 CS域中终结，则需要将发起的呼叫从 CS域中的 GMSC路由至被叫归属 IMS域中的具有 DTF 功能的 AS, 由该 AS进行呼叫的锚定并进行后续可能的域间切换控制， 这里， 为了实现将 CS域的 呼叫路由至 IMS域中的具有 DTF功能的 AS, 需要在 GMSC和被叫归属 IMS域中 MGCF控制下的 MGW之间建立了一段 DTM承载， 这段建立的 DTM承载是也时由于为了实现静态锚点的呼叫控制 方案才引入的， 因此， 同样产生了 DTM承载的路由迂回。 发明内容
本发明的目的在于， 提供一种会话路由路径控制方法和系统， 实现了应用服务器对需要路由至 CS 域中的 IMS域的会话的路由路径控制、 以及应用服务器对需要路由至 IMS域中的 CS域的呼叫的路由 路径控制如就近路由控制等； 本发明减少了 CS域和 MS域之间的 DTM承载和 IP承载转换导致的语音 编解码转换次数， 避免语音业务质量的降低； 并且， 通过本发明还实现了节约 DTM承载， 优化 CS域 和 IMS域之间的 DTM承载， 提高 IP承载的利用率的目的。 ·
为达到上述目的， 本发明提供的一种会话路由路径控制方法， 对于需要从 IMS域路由至电路交 换域的会话， 该方法包括以下步骤：
a、 应用服务器确定出所述会话对应的 IMS域中的网络实体；
b、应用服务器向服务呼叫会话控制功能 S-CSCF提供其确定的所述 IMS域中的网络实体信息，并 由 S-CSCF将所述会话路由至所述 IMS域中的网络实体；
c、 所述 IMS域中的网络实体将所述会话路由至电路交换域中的网络实体。
所述电路交换域为： 移动网络的电路交换 CS域， 或公众电话交换网 PSTN的 CS域。
所述步骤 a具体包括： 应用服务器根据预定承载优化策略确定出所述会话对应的 IMS域中的网络实体。 所述需要从 IMS域路由至电路交换域的呼叫包括： 被叫为电路交换域用户时， 在 IMS域中发起 的主叫侧会话， 或需要在 IMS域中进行锚定过程的电路交换域的被叫侧初始呼叫。
所述步骤 a中预定承载优化策略为： 与该会话曾经路由经过的媒体网关控制功能 MGCF相同； 且所述步骤 a具体包括：
al、 应用服务器获取所述会话对应的呼叫在从电路交换域路由至 IMS域时经过的 MGCF; a2、 应用服务器将该 MGCF确定为所述会话对应的 IMS域中的网络实体信息。
所述步骤 al中： 呼叫在从电路交换域路由至 IMS ¾时经过的 MGCF是由应用服务器根据预定 策略确定的。
步骤 al中的预定策略包括： S定就近路由策略。
所述步骤 al具体包括- al2、 MGCF将其信息承载于邀请 INVITE消息中，并通过 S-CSCF将该消息传输至应用服务器； al3 应用服务器将 INVITE消息中携带的 MGCF的信息确定为需要路由至 CS域的会话曾经路 由经过的 MGCF的信息。
所述步骤 al2的 INVITE消息中还包括： MGCF为该会话分配呼叫参考号， 该呼叫参考号用于 标识会话。
所述步骤 b具体包括： 应用服务器根据所述 MGCF信息构造 CS域路由号码 CSRN, 并将其下 发至 S-CSCF; S-CSCF根据所述 CSRN中的 MGCF信息将所述会话路由至该 MGCF。
所述 CSRN包括： MGCF路由信息和原被叫信息； 或者所述 CSRN包括： MGCF路由信息和原 被叫信息和呼叫参考号。
所述步骤 c还包括： MGCF获取 S-CSCF转发的会话的呼叫参考号， 并根据该呼叫参考号确定 该会话为曾经路由过的会话时， 控制媒体网关功能 MGW不对出呼和入呼的会话进行编解码转换。
所述步骤 a中预定承载优化策略为： 与被叫用户当前 MSC的距离最近的 MGCF; 且所述步骤 a 具体包括： 应用服务器获取需要路由至移动网电路交换 CS域的会话的被叫用户当前位置信息， 并 根据该位置信息确定与被叫用户当前拜访移动交换中心 VMSC距离最近的 MGCF信息。
所述步骤 b具体包括： 应用服务器根据所述 MGCF信息构造 CSRN, 并将其下发至 S-CSCF; S-CSCF根据 MGCF信息确定所述需要路由至电路交换域的会话需要进行跨 IMS域路由时， 将该会 话通过其所在的 IMS域的边界网关控制功能 BGCF、 用户拜访地的 BGCF, 路由至所述 MGCF。
所述步骤 c具体包括： 兼做关口移动交换中心 GMSC的 MGCF从归属位置寄存器 HLR处获取 移动网电路交换 CS域被叫用户的路由信息， 并根据所述路由信息将该会话直接路由至被叫用户当 前所在的 MSC。
步骤 a 中的预定承载优化策略包括： 与该会话曾经路由经过的 MGCF相同或与被叫用户当前 MSC的距离最近的 MGCF; 且所述步骤 a具体包括： 应用服务 ϋ根据预定规则选取一种预定承载优 化策略,并根据选取的承载优化策略确定需要路由至电路交换域的会话对应的 IMS域中的网络实体。
所述步骤 a中的 IMS域中的应用服务器根据预定规则选取一种预定承载优化策略的步骤具体包 括： 应用服务器根据用户偏好设置选取一种预定承载优化策略； 和 /或应用服务器根据被叫用户在电 路交换域的位置信息选取一种预定承载优化策略。
所述用户偏好设置具体包括： 在应用服务器接收到的 INVITE消息中承载有 RN时， 选取与 该会话曾经路由经过的 MGCF相同的承载优化策略； 在应用服务器接收到的 INVITE消息中承载有 使用电话号码描述的资源定位标识 Tel URI H,选取与被叫用户当前 MSC的距离最近的 MGCF的承 载优化策略。
所述应用服务器为： IMS域中具有域间路由功能的应用服务器。
本发明提供一种会话路由路径控制系统， 包括： 位于应用服务器的网络实体确定模块： 对于需 要从 IMS域路由至电路交换域的会话， 确定出会话对应的 IMS域中的网络实体；
位于 IMS域中的 IMS域内路由模块： 获取网络实体确定模块确定的所述 IMS域中的网络实体信 息， 并根据所述网络实体信息将所述需要路由至电路交换域的会话路由至 IMS域网络实体；
位于 IMS域网络实体中的跨域路由模块： 获取需要路由至电路交换域中的网络实体信息， 并将 所述 IMS域内路由模块转发的会话路由至电路交换域中的网络实体。
位于 IMS域中的网络实体的跨域路由模块进一步包括：
IMS域功能子模块： 接收 IMS域内路由模块转发的会话， 并将其路由至电路交换域功能子模块； 电路交换域功能子模块： 对电路交换域中被叫用户的路由进行分析， 并根据路由分析将会话路 由至被叫用户当前所在的交换中心。
本发明还提供一种路由路径控制方法， 对于需要从电路交换域路由至 IMS域的呼叫， 该方法包 括以下步骤：
a、 应用服务器确定出所述呼叫对应的 IMS域中的网络实体；
b、 应用服务器向电路交换域中的网络实体提供其确定的所述 IMS域中的网络实体信息； c、 所述电路交换域中的网络实体将所述呼叫路由至所述 IMS域中的网络实体。
所述需要从电路交换域路由至 IMS域的呼叫包括：需要在 IMS域中进行锚定过程的电路交换域 的呼叫。
所述应用服务器为： IMS域中具有域间路由功能的应用服务器，或移动网电路交换 CS域中具有 域间路由功能的 gsm业务控制功能 gsmSCF, 或具有域间路由功能的信令转发功能 SRF。
所述步骤 a进一步包括：
al、 移动网电路交换 CS域中的发起初始呼叫的 MSC根据预定触发机制将该呼叫触发至所述应 用服务器；
a2、 所述应用服务器根据预定策略确定出需要将该呼叫路由至 IMS域中的 MGCF的信息。 所述移动网电路交换 CS域中的发起初始呼叫为： 主叫侧为 CS域时， VMSC接收到用户设备 UE的呼叫建立消息后发起的呼叫、 或被叫侧为 CS域时， GMSC在接收到来自于主叫侧的呼叫后， 对被叫信息分析后发起的呼叫；
所述预定触发机制为： 移动网络增强逻辑用户应用 CAMEL机制、 或无结构化补充业务数据 USSD机制、 或通知 Notify机制、 或信令拦截机制。 所述步骤 a2具体包括:所述应用服务器获取移动网电路交换 CS域中主叫侧 VMSC的位置信息， 并根据就近策略确定出距离所述 VMSC最近的 MGCF; 或所述应用服务器获取移动网电路交换 CS 域中主叫用户当前的位置信息， 并根据就近策略确定出距离所述主叫用户当前的 VMSC 最近的 MGCF, 或所述应用服务器获取移动网电路交换 CS域中被叫侧 GMSC的位置信息， 并根据预定就 近策略确定所述 GMSC对应的 MGCF。
' 所述应用服务器获取移动网电路交换 CS域中主叫侧 VMSC位置信息的步骤包括：
所述应用服务器根据 CAMEL初始检测点 IDP消息中携带的 MSC地址信息确定 CS域中主叫侧 VMSC的位置信息。
所述应用服务器获取移动网电路交换 CS域中被叫侧 GMSC位置信息的步骤包括- 所述应用服务器根据 CAMEL IDP消息中携带的 MSC地址信息确定移动网电路交换 CS域中被 叫侧 GMSC的位置信息； 或
所述应用服务器根据发送路由信息 SRI消息中携带的 MSC地址信息确定移动网电路交换 CS域 中被叫侧 GMSC的位置信息。
所述步骤 b具体包括： 所述应用服务器根据所述 MGCF信息构造 IMS域路由号码 IMRN, 并将 其下发至 VMSC/GMSC; 或所述应用服务器根据所述 MGCF信息构造 IMRN, 并将其下发至 UE， 所述 UE在发起呼叫时将所述 IMRN提供给其当前所在的 VMSC。
所述 IMRN包括： MGCF路由信息和域间转移功能公共业务标识 DTF PSI和呼叫参考号码； 或 所述 IMRN包括： MGCF路由信息和 DTF PSI。
所述步骤 a还包括： 当应用服务器确定出的 IMS域中的网络实体 MGCF不属于本归属 IMS域 中的网络实体时， MGCF通过对被叫信息进行 E.164域名转换系统 ENUM DNS转换功能来确定出归 属 IMS域中的査询 CSCF I-CSCF地址信息。
本发明提供的路由路径控制系统， 包括：
位于应用服务器的 IMS域网络实体确定模块： 对于需要从电路交换域路由至 IMS域的呼叫，根据 预定策略确定出呼叫需路由至 IMS域中的网络实体， 并将所述 IMS域网络实体信息提供给路由模块； 位于电路交换域的路由模块： 根据 IMS域网络实体确定模块提供的 IMS域网络实体信息， 将呼叫 路由至 IMS域中相应的实体。
本发明提供的应用服务器， 所述应用服务器中设置有 IMS域网络实体确定模块， 对于需要从电 路交换域路由至 IMS域的呼叫，所述 IMS域网络实体确定模块根据预定策略确定出呼叫需要路由至 的 IMS域中的网络实体， 并将所述 IMS域中的网络实体信息提供给电路交换域中的网络实体。
本发明提供的交换中心， 设置于电路交换域中， 所述交换中心中设置有路由模块， 所述路由模 块根据应用服务器提供的 MS域网络实体信息， 将呼叫路由至 IMS域中相应的网络实体。
通过上述技术方案的描述可知， 对于 IMS域中需要路由至 CS域的会话， 本发明中的应用服务 器能够根据网络中具体的路由路径控制需求对上述会话从 IMS域到 CS域的路由路径进行控制， 如 对于从 CS域路由至 IMS域的会话， 需要再从 IMS域中路由回 CS域时， 应用服务器能够裉据承载 优化策略将该会话通过其曾经路由过的 MS域中的网络实体路由回 CS域， 并且由该曾经路由过的 MS域中的网络实体控制对属于同一会话的入呼和出呼两段会话不进行 DTM承载和 IP承载之间的 语音编解码转换， 消除了静态锚点方案下引入的 IP承载路径， 有效减少了会活从 CS域至 IMS域再 到 CS域路由过程中承载的语音编解码转换次数， 避免了语音业务质量的降低； 又如， 对于需要从 IMS域中路由至 CS域的会话，应用服务器能够根据承载优化策略将会话路由至距离 CS域中网络实 体最近的 MGCF， 然后由该 MGCF将会话就近转入 CS域， 尽可能地延长了 IMS域中的 IP承载路 径， 减少了 DTM承载路径， 提高了 IP承载的利用率； 当本发明应用于呼叫连续性课题下的静态错 点方案时，能够有效减少了静态锚点方案中导致的 DTM承载和 IP承载之间的语音编解码转换次数， 减少了静态锚点方案对语音业务质量的影响， 并且通过对会话的路由路径进行优化， 尽可能地延长 引入的 IP承载路径， 减少 DTM承载路径。
对于需要从电路交换域路由至 IMS域的呼叫， 本发明中的应用服务器根据预定路由优化策略对 该呼叫从电路交换域至 IMS域路由路径进行控制， 使得电路交换域中的网络实体能够在应用服务器 的路由控制下将呼叫从指定的 IMS域中的网络实体路由至 IMS域,如应用服务器设定就近路由策略， 则该应用服务器获取电路交换域中发起呼叫网络实体的位置信息， 判断出距离该电路交换域发起呼 叫网络实体最近的 IMS域中网络实体， 然后， 应用服务器向电路交换域中发起呼 ^网络实体提供该 IMS域中网络实体的路由信息， 使得电路交换域中的网络实体能够根据获得的路由信息将呼叫从指 定的 IMS域网络实体就近路由至 IMS域， 使 CS域与 IMS域之间的 DTM承载的路径最短， 从而节 省了 DTM承载， 减少了可能的路由迂回； 当本发明应用于呼叫连续性课题下的静态锚点方案时， 有效减少了静态锚点方案中引入的 DTM承载迂回路径。
本发明的上述优点增加了静态锚点方案的优势， 提高了静态锚点方案的实用性。 附图简要说明
图 1是 CS域的用户作为主叫发起呼叫时， CS域中使用 CAMEL机制将发起的呼叫触发至具有 DTF 功能的 AS进行锚定的流程图； ,
图 2是 CS域的用户做被叫时， CS域中使用 CAMEL机制将入局的呼叫触发至具有 DTF功能的 AS 进行锚定的流程图；
图 3是 CS域的用户做被叫时， CS域中使用信令控截机制将入局的呼叫触发至具有 DTF功能的 AS 进行锚定的流程图 ·； .
图 4是 CS域或 网络的用户做主叫用户时， IMS域中的 MSISDN用户做被叫用户时， CS域或 PSTN网络根据对被叫号码的分析将呼叫路由至 IMS域并触发至锚点 AS进行锚定的流程图；
图 5是本发明实施例的会话路由路径控制系统示意图一；
图 6是本发明实施例的 DTM承载优化示意图；
图 7是本发明实施例的会话路由路径控制系统示意图二。 实施本发明的方式
本发明的第一个核心技术内容是， 当会话需要从 IMS域路由至电路交换域时， 如果应用服务器 能够根据预定路由策略控制会话的路由路径， 就能够实现不同的对路由优化或承载优化的目的， 如 在呼叫连续性课题下的静态锚点方案中， 如果 IMS域中的 MGCF能够将会话就近路由至电路交换域， 则能够尽可能的延长由于静态锚点方案引入的 IP承载路径， 减少了 DTM承载路径， 优化了会话的 DTM承载路径； 如果能够将会话从其曾经路由过的 IMS网络实体路由回电路交换域， 则能够消除了 静态锚点方案下引入的 IP承载路径,有效减少呼叫从电路交换域至 IMS域再到电路交换域路由过程中 的编解码转换的次数。
下面基于本发明的第一个核心技术内容对本发明提供的技术方案在有效减少编解码转换的次数 方面做进一步的描述。
对于移动网电路交换 CS域的用户作被叫， 当呼叫路由至被叫用户的 GMSC时， GMSC使用网络 侧控制的 CAMEL机制或信令拦截机制将发起的呼叫触发至具有 CSAF的 gsmSCF或 SR 进行呼叫的 路由控制， 然后， 具有 CSAF的 gsmSCF或 SRF根据一定的路由策略生成一个指向 IMS域中的具有 DTF 功能的一个 AS的路由号码 IMRN， 并使用 CAMLE connect操作或 SRI-Ack消息将 IMRN下发给 GMSC。 这里， 具有 CSAF的 gsmSCF或 SRF在分配 IMRN时除了需要保证分配的 IMRN能够指向一个具有 DTF 功能的 AS之外， 还需要保证 GMSC能够根据其分配的 IMRN将呼叫固定选择一个 IMS域中的 MGCF, 然后 GMSC根据 IMRN向该 MGCF发送 IAM消息， 使该呼叫路由至 IMS域。后续 MGCF根据 IMRN将会 话经由 I-CSCF转发至具有 DTF功能的 AS, 具有 DTF功能的 AS接收到的被叫信息包含 DTF PSI信息的 IMRN的会话后， 对会话进行锚定控制， 即触发 B2BUA功能， 终止掉 AS接收到的会话， 然后发起一 个针对原被叫信息的新会话， 即具有 DTF功能的 AS通过同 HSS的 Sh接口获得被叫用户侧的 S-CSCF信 息， 然后， 将会话路由至 S-CSCF, 并由该 S-CSCF将会话路由至原被叫侧。 这里， 具有 DTF功能的 AS发起一个针对原被叫信息的新会话时， 需要由具有 CSAF的 AS对原被叫信息进行路由分析， 在具 有 CSAF的 AS判断出需要将会话路由至移动网电路交换 CS域中进行接续时， 具有 CSAF的 AS基于原 被叫信息构造 TEL URI格式的 CSRN,然后具有 DTF功能的 AS发起的针对原被叫信息的新会话中的被 叫信息 Requested-URI为 CSRN。具有 CSAF的 AS分配的 CSRN需要能够保证被叫用户侧的 S-CSCF能够 将会话路由回与 GMSC使用 MRN将呼叫路由至 IMS域时相同的 MGCF, 然后， MGCF根据 CSRN将呼 叫路由至 GMSC。 当 MGCF判断出自己接收到的呼叫即 MGCF接收到的 GMSC向其发送的 IAM消息， 和自己发出的呼叫即 MGCF向 GMSC发送的 IAM消息属于同一个呼叫时， 此时 MGCF控制 MGW对入 呼和出呼的会话不进行编解码转换， 即 MGCF对于接收到的 GMSC发送的 IAM消息， 控制 MGW不将 其 DTM承载转换成 IP承载， MGCF对于向 GMSC发出的 IAM消息， 控制 MGW直接使用其先前接收到 的 DTM承载， 从而使得 GMSC发起的到 MGW的 DTM承载中的语音业务能够无损地接续到 MGW发起 的到 GMSC的 DTM承载中的语音业务上。
上述具有 CSAF的 gsmSCF或 SRF分配的 IMR 需要能够保证 GMSC能够固定选择一个 IMS 域中的 MGCF的过程可以通过 RN的构成来实现， 如 IMRN的构成可以是 "路由前缀 +DTF PSI+ 呼叫参考号" 的方式， 根据该路由前缀 GMSC能够固定寻址到 IMS域中某一个指定的 MGCF。
上述具有 CSAF的 AS分配的 CSR 需要能够保证将会话路由回与 GMSC使用 IMR 将呼叫路 由至 IMS域时相同的 MGCF的过程可以通过 CSRN的构成来实现， 如 CSRN的构成可以是 "路由 前缀 +原被叫信息 +呼叫参考号" 的方式， 根据该路由前缀 S-CSCF能够固定寻址到 IMS域中某一 个指定的 MGCF。
上述 MGCF判断出自己接收到的呼叫即 MGCF接收到的 GMSC向其发送的 IAM消息，和自己 发出的呼叫即 MGCF向 GMSC发送的 IAM消息属于同一个呼叫的过程可以通过判断其发出的呼叫 中的被叫信息即 CSRN中的呼叫参考号和其接收到的呼叫中的被叫信息即 IMRN中的呼叫参考号是 否相同的方式来判断。
这里， MGCF也可以通过对自己发出的会话即 MGCF根据 IMRN向具有 DTF功能的 AS发送 的 INVITE消息， 和接收到的会话即具有 DTF功能的 AS根据 CSRN向 MGCF发送的 INVITE消息 进行判断的方法来判断两段会话是否属于同一个会话。 同样的， 可以通过判断 MGCF发出的会话中 的被叫信息即 IMRN中的呼叫参考号和 MGCF接收到的会话中的被叫信息即 CSRN中的呼叫参考号 是否相同的方式来判断。
除了使用判断两段呼叫 /会话中的被叫信息 RN中的呼叫参考号和被叫信息 CSRN中的呼叫参 考号是否相同的方式来确定两段呼叫 /会话是否属于同一个呼叫 /会话之外, MGCF还可以通过在自己 发出的会话信息中增加相关参数，并且具有 DTF功能的 AS在新发起的会话中传递 MGCF增加的相 关参数， 从而 MGCF通过判断其发出的会话中和其接收到的会话中是否包含相同的相关参数信息的 方式来判断两段会话是否属于同一个会话。如 MGCF可在自己发出的会话中的主 /被叫信息中增加自 身分配的呼叫参考号， 然后通过 I-CSCF将该会话发送至具有 DTF功能的 AS中， 具有 DTF功能的 AS触发 B2BUA功能， 终止掉 AS接收到的会话， 然后发起一个针对原被叫信息的新会话， 该新会 话中的主 /被叫信息中同样包含 MGCF分配的呼叫参考号，然后将该新的会话经由 S-CSCF转发至同 —个 MGCF。从而， MGCF判断其发出的会话中的主 /被叫信息中的呼叫参考号和其接收到的会话中 的主 /被叫信息中的呼叫参考号是否相同的方式来判断该两段会话是否属于同一个会话。 进一步的， MGCF在分配呼叫参考号时， 可以在呼叫参考号中包含 GMSC在向 MGCF发送的 IAM消息时选择 的某一个的 MGW信息， 从而当 MGCF接收到 S-CSCF向其发送的会话时， 根据呼叫参考信息， 在 MGCF判断当 MGCF判断出自己接收到的呼叫和自己发出的呼叫属于同一个呼叫时， MGCF进一步 根据呼叫参考号信息中的 MGW信息， 控制会话选择与先前呼叫相同的 MGW, 进而 MGCF控制该 MGW对入呼和出呼的会话不进行编解码转换。
上述应用服务器确定 IMS域网络实体的出发点在于减少编解码的转换次数， 以保证语音业务的 质量，因此需要在 MGCF将同一次呼叫下的入 IMS域和出 IMS域的两段呼叫进行关联，并控制 MGW 对入呼和出呼的会话不进行编解码转换。
下面基于本发明的第一个核心技术内容对本发明提供的技术方案在减少 DTM承载路径以优化
DTM承载路径方面做进一步的描述。
核心技术内容当会话需要从 MS域路由至电路交换域时， 如果应用服务器能够根据预定路由策 略控制会话的路由路径， 就能够实现不同的对路由优化或承载优化的目的， 如在呼叫连续性课题下 的静态锚点方案中， 如果 IMS域中的 MGCF能够将呼叫就近路由至 CS域的 VMSC/GMSC, 则能够尽 可能缩短了 DTM承载路径， 延长了 IP承载的使用， 优化了会活的 DTM承载路径。 具体的说， 当具有 CSAF的 AS判断出呼叫需要从 IMS域路由至电路交换域时， 则具有 CSAF 的 AS在分配 CSRN时， 考虑到被叫当前在电路交换域的位置信息， 分配的 CSRN能够将 S域的 会话路由至距离当前被叫当前所在的 VMSC最近的 MGCF, 使得会话能够就远出 IMS域， 后续呼 叫在该 MGCF和 VMSC之间接续， 延长了使用的 BP承载， 缩短了 DTM承载， 提高了 IP承载的利 用率， 为运营商降低了网络运营成本。
上述具有 CSAF的 AS在分配的 CSRN时考虑到被叫用户在 CS域的位置信息可通过具有 CSAF 的 AS向被叫用户的 HLR査询被叫用户当前的注册状态的过程来实现， 即具有 CSAF的 AS向 HLR 发送 ATI (Any Time Interrogation随时査询） 实现。 具有 CSAF的 AS根据 HLR返回的 ATI Ack消 息中的 Location Information信息可以判断出用户当前所在的位置信息。
上述的具有 CSAF的 AS分配的 CSRN能够将 IMS域的会活路由至距离当前被叫当前所在的
VMSC最近的 MGCF, 使得会话能够就远出 IMS域的过程可以通过 CSR 的构成来实现： 如 CSRN 的构成可以是 "路由前缀 +原被叫信息 +呼叫参考号" 的方式， 具有 CSAF的 AS在分配 CSRN时 参考被叫用户当前移动网电路交换 CS域的位置信息， 分配能够寻址到距离被叫用户当前移动网电 路交换 CS域的 VMSC最近的 MGCF的路由前缀。
另外， 上述 CSRN的构成也可以直接是 MSRN的形式， 即由分配 CSRN的具有 CSAF的 AS直 接向被叫侧的 HLR发送取漫游号码操作，获取被叫用户的 MSRK，根据 MSRN将呼叫直接从 CSAF 经由 S-CSCF和 MGCF路由至用户当前所在的 VMSC后接续。
上述 S-CSCF根据 CSRN的路由前缀或是根据具有 CSAF的 AS获取的 MSRN选择 MGCF时， 当 S-CSCF根据 CRSN的路由前缀判断出需要路由的 MGCF不属于本 IMS域即用户归属的 IMS域 时， 如用户漫游时， 用户归属 MS域不能覆盖到用户当前拜访的移动网电路交换 CS域， 则此时需 要跨 IMS域进行路由， 则 S-CSCF选择本 IMS域的 BGCF, 将会话路由至 BGCF, 本域的 BGCF根 据 CSRN的路由前缀或是 MSRN将呼叫路由至用户拜访地的 IMS域中的 BGCF,后续用户拜访地的 IMS域中的 BGCF根据路由前缀或是 MSRN寻址到距离用户当前 VMSC最近的用户拜访地的 IMS 域中的 MGCF, 然后将呼叫路由至该 MGCF, MGCF根据原被叫信息将呼叫转发至被叫用户当前所 在移动网电路交换 CS域实体， 即 MGCF是跟据 CSR 中的原被叫信息将呼叫转发至被叫用户当前 所在移动网电路交换 CS域的 GMSC, 或是根据 MSRN将呼叫转发至被叫用户当前所在移动网电路 交换 CS域的 VMSC。
这里， 当 MGCF是跟据 CSRN中的原被叫信息进行呼叫的转发时， 则 MGCF在接收到 S-CSCF 或 BGCF转发的会话时， 需要根据被叫信息进行被叫路由分析， 为了避免 MGCF对被叫信息的分析 后将呼叫再度送回被叫用户归属移动网电路交换 CS 域的 GMSC , 这里 MGCF 在接收到 S-CSCF/BGCF的 INVITE消息后， MGCF需要兼做 GMSC, 完成向 HLR对移动网电路交换 CS域 被叫用户取漫游号码操作并获取用户的 MSRN, 根据 MSRN将呼叫直接从 MGCF/GMSC路由至用 户当前所在的 VMSC后进行接续。
进一步的， 由于一个 MGCF可以控制多个 MGW， MGCF在接收到 S-CSCF或是 BGCF的 INVITE消息， 在建立 DTM承载时， 可根据获取的用户的路由信息， 即通过 MGCF兼做 GMSC向 HLR完成对移动网电路交换 CS域被叫用户取漫游号码操作获得用户当前所在的 MSRN, 从而判断 出被叫用户当前所在的 VMSC地址信息， MGCF选取距离该 VMSC最近的 MGW来建立 MGW到 VMSC之间的 DTM承载， 从而使得 VMSC和 MGW之间建立的 DTM承载最短， 进一步优化了呼 叫由移动网电路交换 CS域路由至 MS域之间的 DTM承载。
下面以需要在 IMS域中进行静态锚定的被叫侧会话为例对本发明提供的基于第一个核心技术内 容以有效减少编解码转换的次数的技术方案做进一步的描述。
当本发明应用于呼叫连续性课题下的静态锚点方案时， 本发明的应用服务器为 IMS域中的具有 域间路由控制功能的 AS, 即具有 CSAF的 AS。 IMS 域中的网络实体为多个处于不同地域位置的 MGCFo
下面结合附图 2、 附图 4对本发明的多种实现方法进行详细描述。
附图 2为移动网电路交换 CS域的用户做被叫时, IMS域中的 CSAF采用与该会话曾经路由经过 的 MGCF相同的承载优化策略， 且移动网电路交换 CS域中使用 CAMEL机制将入局的呼叫触发至 具有 DTF功能的 AS进行锚定的流程图。
在该流程中， 本发明的改进点主要在步骤 2-6和步骤 2-10〜步骤 2-13， 其它步骤与背景技术中描述 的步骤基本相同。
在步骤 2-6、 具有 CSAF的 gsmSCF生成一个指向 IMS域中的具有 DTF功能的一个 AS的路由号码 IMRN,使得 GMSC根据该路由号码将呼叫路由至该 DTF上。其中 IMRN的构成可以是 "路由前缀 +DTF PSI+呼叫参考号" ， 这里， 路由前缀用于指示 GMSC能够固定寻址到 IMS域中的某一个 MGCF, DTF PSI用于指示将呼叫需要锚定在 IMS域中某一个具有 DTF功能的 AS， 呼叫参考号用于唯一标识一个呼 叫。 进一步的， 为了节省 DTM承载， 具有 CSAF的 gsmSCF在分配路由前缀时， 可以稂据 GMSC的地 址信息来分配距离 GMSC最近的 MGCF对应的路由前缀， 使得 GMSC能够将呼叫就近路由至 MS域。 然后具有 CSAF的 gsmSCF通过 CAMEL connect消息将 IMRN下发给 GMSC。
在步骤 2-10〜步骤 2-13、 具有 DTF功能的 AS接收到的被叫信息包含 DTF PSI信息的 MRN的会话 后， 对会话进行锚定控制， 即触发 B2BUA (背靠背用户代理）功能， 终止掉 AS接收到的会话， 然后 发起一个针对原被叫信息的新会话， 即具有 DTF功能的 AS通过同 HSS的 Sh接口获得被叫用户侧的 S-CSCF信息， 然后， 将会话路由至 S-CSCF， 并由该 S-CSCF将会话路由至原被叫侧。其中 CSRN的构 成可以是 "路由前缀 +原被叫信息 +呼叫参考号"， 这里， 路由前缀用于指示 S-CSCF能够固定寻址到 某一个 MGCF, CSAF分配同步骤 2-6中分配的 IMRN中相同的路由前缀， 以保证 S-CSCF能够将会话路 由回步骤 2-6中 GMSC将呼叫路由至的相同的 MGCF, 原被叫信息用于指示将真正呼叫应该接续的被 叫信息， 呼叫参考号用于 MGCF识别接收到哪两段呼叫 （入局呼叫和出局呼叫） 属于同一个呼叫。
这里， 具有 DTF功能的 AS发起一个针对原被叫信息的新会话时， 需要由具有 CSAF的 AS对原被 叫信息进行路由分析， 在具有 CSAF的 AS判断出需要将会话路由至移动网电路交换 CS域中进行接续 时， 具有 CSAF的 AS基于原被叫信息构造 TEL URI格式的 CSRN, 然后具有 DTF功能的 AS发起的针对 原被叫信息的新会话中的被叫信息 Requested-URI为 CSRN。
这里， 在 S-CSCF将呼叫路由至原被叫侧的过程中， 当原被叫信息为 TEL URI格式时， S-CSCF执 行 ENUM DNS转换功能， 如果能够将原被叫号码转换成 SIP URI格式， 则后续的呼叫路由在 IMS域中 进行， 否则， S-CSCF将呼叫路由至本 IMS域的 BGCF, 由 BGCF将呼叫最终经由 MGCF路由至移动网 电路交换 CS域的 GMSC,最后由 GMSC将呼叫接续至被叫。在具有 DTF功能的 AS启用 B2BUA功能时， 对于在 DTF终止的会话和在 DTF新发起的会话， DTF均对其维护状态， 以对后续用户可能发起的域间 切换进行控制。
MGCF在接收到 S-CSCF或 BGCF发送的会话时， MGCF根据被叫信息 CSRN中的呼叫参考号 MGCF判断出自己接收到的呼叫即在步骤 2-8中 MGCF接收到的 GMSC发送的 IAM，和 MGCF发送的会 话即本步骤中 MGCF将向 GMSC发送的 IAM属于同一个呼叫时， 此时 MGCF控制 MGW对入呼和出呼 的会话不进行编解码转换， 即 MGCF对于接收到的 GMSC发送的 IAM消息， 控制 MGW不将其 DTM7?: 载转换成 IP承载， MGCF对于向 GMSC发出的 IAM消息， 控制 MGW直接使用其先前接收到的 DTM承 载， 从而使得 GMSC发起的到 MGW的 DTM承载中的语音业务能够无损地接续到 MGW发起的到 GMSC的 DTM承载中的语音业务上。
附图 3为移动网电路交换 CS域的用户做被叫时， IMS域中的 CSAF釆用与该会话曾经路由经 过的 MGCF相同的承载优化策略， 且移动网电路交换 CS域中使用信令拦截机制将入局的呼叫触发 至具有 DTF功能的 AS进行锚定的流程图。
在该流程中， 本发明的改进点主要在步骤 3-5和步骤 3-9~步骤 3-12, 其它步骤与背景技术中描述 的步骤基本相同。
在步骤 3-5、具有 CSAF的 SRF生成一个指向 IMS域中的具有 DTF功能的一个 AS的路由号码 IMRN, 使得 GMSC根据该路由号码将呼叫路由至该 DTF上。 其中 IMRN的构成可以是 "路由前缀 +DTF PSI+ 呼叫参考号" ， 这里， 路由前缀用于指示 GMSC能够固定寻址到 IMS域中的某一个 MGCF, DTF PSI 用于指示将呼叫需要锚定在 IMS域中某一个具有 DTF功能的 AS，呼叫参考号用于唯一标识一个呼叫。 进一步的， 为了节省 DTM承载， 具有 CSAF的 SRF在分配路由前缀时， 可以根据 GMSC的地址信息来 分配距离 GMSC最近的 MGCF对应的路由前缀， 使得 GMSC能够将呼叫就近路由至 IMS域。 然后具有 CSAF的 SRF模仿 HLR的功能相 GMSC返回 SRI-Ack消息， 该 SRI-Ack消息中将 IMRN作为被.叫路由信 息发送给 GMSC。
在步骤 3-9〜步骤 3-12、具有 DTF功能的 AS接收到的被叫信息包含 DTF PSI信息的 IMRN的会话后， 对会话进行锚定控制， 即触发 B2BUA (背靠背用户代理）功能， 终止掉 AS接收到的会话， 然后发起 —个针对原被叫信息的新会话， 即具有 DTF功能的 AS通过同 HSS的 Sh接口获得被叫用户侧的 S- SCF 信息， 然后， 将会话路由至 S-CSCF, 并由该 S-CSCF将会话路由至原被叫侧。 其中 CSRN的构成可以 是 "路由前缀 +原被叫信息 +呼叫参考号"， 这里， 路由前缀用于指示 S-CSCF能够固定寻址到某一个 MGCF, CSAF分配同步骤 6中分配的 IMRN中相同的路由前缀， 以保证 S-CSCF能够将会话路由回步 骤 6中 GMSC将呼叫路由至的相同的 MGCF, 原被叫信息用于指示将真正呼叫应该接续的被叫信息， 呼叫参考号用于 MGCF识别接收到哪两段呼叫 （入局呼叫和出局呼叫） 属于同一个呼叫。
这里， 具有 DTF功能的 AS发起一个针对原被叫信息的新会话时， 需要由具有 CSAF的 AS对原被 叫信息进行路由分析， 在具有 CSAF的 AS判断出需要将会话路由至移动网电路交换 CS域中进行接续 时， 具有 CSAF的 AS基于原被叫信息构造 TEL URI格式的 CSRN, 然后具有 DTF功能的 AS发起的针对 原被叫信息的新会话中的被叫信息 Requested-URI为 CSRN。
这里， 在 S-CSCF将呼叫路由至原被叫侧的过程中， 当原被叫信息为 TEL URI格式时， S-CSCF执 行 ENUM DNS转换功能， 如果能够将原被叫号码转换成 SEP URI格式， 则后续的呼叫路由在 MS域中 进行， 否则， S-CSCF将呼叫路由至本 IMS域的 BGCF, 由 BGCF将呼叫最终经由 MGCF路由至移动网 电路交换 CS域的 GMSC,最后由 GMSC将呼叫接续至被叫。在具有 DTF功能的 AS启用 B2BUA功能时， 对于在 DTF终止的会话和在 DTF新发起的会话， DTF均对其维护状态， 以对后续用户可能发起的域间 切换进行控制。
MGCF在接收到 S-CSCF或 BGCF发送的会话时， MGCF根据被叫信息 CSRN中的呼叫参考号 MGCF判断出自己接收到的呼叫即在步骤 8中 MGCF接收到的 GMSC发送的 IAM， 和 MGCF发送的会 话即本步骤中 MGCF将向 GMSC发送的 IAM属于同一个呼叫时， 此时 MGCF控制 MGW对入呼和出呼 的会话不进行编解码转换， 即 MGCF对于接收到的 GMSC发送的 IAM消息， 控制 MGW不将其 DTM承 载转换成 IP承载， MGCF对于向 GMSC发出的 IAM消息， 控制 MGW直接使用其先前接收到的 DTM承 载， 从而使得 GMSC发起的到 MGW的 DTM承载中的语音业务能够无损地接续到 MGW发起的到 GMSC的 DTM承载中的语音业务上。
附图 4为 CS域或 PSTN网络的用户做主叫用户时， IMS域中的 CSAF采用与该会话曾经路由经过的 MGCF相同的承载优化策略， 且 IMS域中的 MSISDN用户做被叫用户 , CS域或 PSTN网络中根据对被 叫号码的分析将呼叫路由至 IMS域并触发至 AS进行锚定的流程图。
在该流程中， 本发明的改进点主要在步骤 4-2和步骤 4-7〜步骤 4-9, 其它步骤与背景技术中描述的 步骤基本相同。
在步骤 4-2、 MGCF将 MSISDN转换成 TEL URI,并向 I-CSCF发送 INVITE消息。 MGCF在向 I-CSCF 发送 INVITE消息中，其被叫信息 Requested-URI的构成为 "路由前缀 +被叫信息如 TEL URI+呼叫参考 号" 的形式， 这里， 路由前缀用于指示 S-CSCF能够固定寻址回该 MGCF, MGCF分配的呼叫参考号 用于 MGCF识别接收到哪两段呼叫即入局呼叫和出局呼叫属于同一个呼叫， 进一步的， 该呼叫参考 号还可以包含 CS域或 PSTN网络发起的呼叫时选择的 MGW信息。
在步骤 4-7、 具有 CSAF的 AS通过对被叫信息进行路由分析， 在具有 CSAF的 AS判断出需要将会 话路由至移动网电路交换 CS域中迸行接续时， 具有 CSAF的 AS基于原被叫信息构造 TEL URI格式的 CSRN, 然后触发 DTF功能。 其中， CSR 的构成可以是 "路由前缀 +原被叫信息 +呼叫参考号" ， 这 里，路由前缀用于指示 S-CSCF能够固定寻址到某一个 MGCF,具有 CSAF的 AS分配同步骤 4-2中 MGCF 在 INVITE消息中携带的相同的路由前缀，以保证 S-CSCF能够将会话路由回步骤 4-1中 CS域或是 PSTN 网络将呼叫路由至的相同的 MGCF, 原被叫信息用于指示将真正呼叫应该接续的被叫信息， 呼叫参 考号用于 MGCF识别接收到哪两段呼叫即入周呼叫和出局呼叫属于同一个呼叫， 这里， 具有 CSAF的 AS分配同步骤 2中 MGCF在 INVITE消息中携带的相同的呼叫参考号。
在步骤 4-8~4-9、 具有 DTF功能的 AS对具有 CSAF的 AS接收到的会话进行锚定控制， 即触发 B2BUA功能， 终止掉 AS接收到的会话， 然后发起一个针对原被叫信息的新会话， 该新会话中的被叫 信息 Requested-URI为具有 CSAF的 AS构造的 CSRN。即具有 DTF功能的 AS通过同 HSS的 Sh接口获得被 叫用户侧的 S-CSCF信息， 然后， 将会话路由至 S-CSCF, 并由该 S-CSCF将会话路由至原被叫侧。
这里， 在 S-CSCF将会话路由至原被叫侧的过程中， 由于具有 DTF功能的 AS新发起的会话中的
Requested-URI为 CSRN, S-CSCF经过 ENUM DNS转换功能后不能将其转换成 SIP URI格式， 因此 S-CSCF将会话路由至本 IMS域的 BGCF, 由 BGCF将会话转发至 MGCF路由至移动网电路交换 CS域的
GMSC。 MGCF在接收在 BGCF或 S-CSCF发送的会话时， 根据呼叫参考号 MGCF判断出自己接收到的 会话即在步骤 4-1中 MGCF接收到的 CS域或 PSTN网络发送的 IAM消息， 和发送的会话即本步骤中
MGCF向 CS域或 PSTN网络发送的 IAM消息属于同一个呼叫 , 此时 MGCF控制 MGW对入呼和出呼的 会活不进行编解码转换， 即 MGCF对于接收到的 GMSC发送的 IAM消息， 控制 MGW不将其 DTM承载 转换成 IP承载， MGCF对于向 GMSC发出的 IAM消息，控制 MGW直接使用其先前接收到的 DTM承载， 从而使得 CS域或 PSTN网络发起的到 MGW的 DTM承载中的语音业务能够无损地接续到 MGW发起的 到 CS域或 PSTN网络的 DTM承载中的语音业务上。
在具有 DTF功能的 AS启用 B2BUA功能时， 对于在 DTF终止的会话和在 DTF新发起的会话， DTF 均对其维护状态， 以对后续用户可能发起的域间切换进行控制。
下面以需要在 IMS域中进行静态锚定的被叫侧会话为例对本发明的提供的基于第一个核心技术 内容来减少 DTM承载路径以优化 DTM承载路径的技术方案做进一步的描述。
附图 2为移动网电路交换 CS域的用户做被叫时， IMS域中的 CSAF采用与被叫用户当前 MSC 的距离最近的 MGCF的承载优化策略， 且移动网电路交换 CS域中使用 CAMEL机制将入局的呼叫 触发至具有 DTF功能的 AS迸行铺定的流程图。
在该流程中， 本发明的改进点主要在步骤 2-10〜步骤 2-13， 其它步骤与背景技术中描述的步骤基 本相同。
在步骤 2-10〜步骤 2-13、 具有 DTF功能的 AS接收到的被叫信息包含 DTF PSI信息的 IMRN的会话 后， 对会话进行锚定控制， 即触发 B2BUA (背靠背用户代理）功能， 终止掉 AS接收到的会话， 然后 发起一个针对原被叫信息的新会话， 即具有 DTF功能的 AS通过同 HSS的 Sh接口获得被叫用户侧的 S-CSCF信息， 然后， 将会话路由至 S-CSCF, 并由该 S-CSCF将会话路由至原被叫侧。其中 CSRN的构 成可以是 "路由前缀 +原被叫信息 +呼叫参考号"， 这里， 路由前缀用于指示 S-CSCF能够固定寻址到 某一个 MGCF。 CSAF在分配 CSRN之前， 可先向 HLR发送 ATI, 查询用户当前移动网电路交换 CS域 的注册状态， 并根据 HLR返回的 ATI Ack消息中的 Location lnforaiation信息可以判断出用户当前所在 的位置信息， 然后 CSAF分配能够寻址到距离被叫用户当前移动网电路交换 CS域的 VMSC最近的 MGCF的路由前缀。 .
这里， 具有 DTF功能的 AS发起一个针对原被叫信息的新会话时， 需要由具有 CSAF的 AS对原被 叫信息进行路由分析， 在具有 CSAF的 AS判断出需要将会话路由至移动网电路交换 CS域中进行接续 时， 具有 CSAF的 AS基于原被叫信息构造 TEL URI格式的 CSRN, 然后具有 DTF功能的 AS发起的针对 原被叫信息的新会话中的被叫信息 Requested-URI为 CSRN。
这里， 在 S-CSCF将呼叫路由至原被叫侧的过程中， 当原被叫信息为 TEL URI格式时， S-CSCF执 行 ENUM DNS转换功能， 如果能够将原被叫号码转换成 SIP URI格式， 则后续的呼叫路由在 IMS域中 进行， 否则， S-CSCF将呼叫路由至本 IMS域的 BGCF， 由 BGCF将呼叫最终经由 MGCF路由至移动网 电路交换 CS域的 GMSC, 最后由 GMSC将呼叫接续至被叫。 在 S-CSCF将呼叫转发至 MGCF时， 当 S-CSCF根据 CRSN的路由前缀判断出需要路由的 MGCF不属于本 IMS域即用户归属的 IMS域时， 如用 户漫游时， 用户归属 IMS域不能覆盖到用户当前拜访的移动网电路交换 CS域， 则此时需要跨 IMS域 进行路由， 贝 IJS-CSCF选择本 MS域的 BGCF, 将会话路由至 BGCF, 本域的 BGCF根据路由前缀将呼 叫路由至用户拜访地的 IMS域中的 BGCF， 后续 BGCF根据路由前缀寻址到距离用户当前 VMSC最近 的 MGCF, 然后将呼叫路由至该 MGCF。 该 MGCF实体兼做 GMSC实体， 实体中的 MGCF功能向内部 的 GMSC功能发送 IAM消息。
在具有 DTF功能的 AS启用 B2BUA功能时， 对于在 DTF终止的会活和在 DTF新发起的会话， DTF 均对其维护状态， 以对后续用户可能发起的域间切换进行控制。
在步骤 2-14、 MGCF/GSMC实体中的 GMSC功能接收到 MGCF功能的入局呼叫 IAM消息后， 使用 智能网业务的方式或是其他的转换技术从中解析出原被叫用户的 MSISDN，然后 GMSC基于解析出的 MSISDN向 HLR发送 SRI消息。
附图 3为移动网电路交换 CS域的用户做被叫时， IMS域中的 CSAF采用与被叫用户当前 MSC 的距离最近的 MGCF的承载优化策略， 且移动网电路交换 CS域中使用信令拦截机制将入局的呼叫 触发至具有 DTF功能的 AS进行锚定的流程图。
在该流程中， 本发明的改进点主要在步骤 3-9〜步骤 3-12和步骤 3-14， 其它步骤与背景技术中描述 的步骤基本相同。
在步骤 3-9~步骤 3-12、具有 DTF功能的 AS接收到的被叫信息包含 DTF PSI信息的 IMRN的会话后， 对会话进行锚定控制， 即触发 B2BUA (背靠背用户代理）功能， 终止掉 AS接收到的会话， 然后发起 一个针对原被叫信息的新会话， 即具有 DTF功能的 AS通过同 HSS的 Sh接口获得被叫用户侧的 S-CSCF 信息， 然后， 将会话路由至 S-CSCF, 并由该 S-CSCF将会话路由至原被叫侧。 其中 CSRN的构成可以 是 "路由前缀 +原被叫信息 +呼叫参考号"， 这里， 路由前缀用于指示 S-CSCF能够固定寻址到某一个 MGCFo CSAF在分配 CSRN之前， 可先向 HLR发送 ATI, 査询用户当前移动网电路交换 CS域的注册 状态， 并根据 HLR返回的 ATI Ack消息中的 Location Information信息可以判断出用户当前所在的位置 信息，然后 CSAF分配能够寻址到距离被叫用户当前移动网电路交换 CS域的 VMSC最近的 MGCF的路 由前缀。
这里， 具有 DTF功能的 AS发起一个针对原被叫信息的新会话时， 需要由具有 CSAF的 AS对原被 叫信息进行路甴分析， 在具有 CSAF的 AS判断出需要将会话路由至移动网电路交换 CS域中迸行接续 时， 具有 CSAF的 AS基于原被叫信息构造 TEL URI格式的 CSRN, 然后具有 DTF功能的 AS发起的针对 原被叫信息的新会话中的被叫信息 Requested-URI为 CSRN。
. 这里， 在 S-CSCF将呼叫路由至原被叫侧的过程中， 当原被叫信息为 TEL URI格式时， S-CSCF执 行 ENUM DNS转换功能， 如果能够将原被叫号码转换成 SIP URI格式， 则后续的呼叫路由在 IMS域中 进行， 否则， S-CSCF将呼叫路由至本 IMS域的 BGCF, 由 BGCF将呼叫最终经由 MGCF路由至移动网 电路交换 CS域的 GMSC， 最后由 GMSC将呼叫接续至被叫。 在 S-CSCF将呼叫转发至 MGCF时， 当 S-CSCF根据 CRSN的路由前缀判断出需要路由的 MGCF不属于本 MS域即用户归属的 IMS域时， 如用 户漫游时， 用户归属 IMS域不能覆盖到用户当前拜访的移动网电路交换 CS域， 则此时需要跨 IMS域 进行路由， 则 S-CSCF选择本 IMS域的 BGCF, 将会话路由至 BGCF, 本域的 BGCF根据路由前缀将呼 叫路由至用户拜访地的 IMS域中的 BGCF, 后续 BGCF根据路由前缀寻址到距离用户当前 VMSC最近 的 MGCF, 然后将呼叫路由至该 MGCF。 该 MGCF实体兼做 GMSC实体， 实体中的 MGCF功能向内部 的 GMSC功能发送 IAM消息。 '
在具有 DTF功能的 AS启用 B2BUA功能时， 对于在 DTF终止的会话和在 DTF新发起的会话， DTF 均对其维护状态， 以对后续用户可能发起的域间切换进行控制。
在步骤 3-14、 MGCF/GSMC实体中的 GMSC功能接收到 MGCF的入局呼叫 IAM消息后， 可使用某 种转换技术从中解析出原被叫用户的 MSISDN，然后，基于解析出的 MSISDN对被叫信息进行分析后， MGCF/GSMC实体中的 GMSC功能向 HLR发送 SRI消息以获得被叫用户的路由信息。该呼叫同样被具 有 CSAF的 SRF拦截下来， 具有 CSAF的 SRF判断出已经对本次呼叫进行了处理， 则不对该栏截下来的 SRI进行分析， 不执行相应的域间路由策略控制处理， 直接向 HLR转发该 SRI消息， 并将其接收到的 HLR返回的 SRI-Ack消息转发至 MGCF/GSMC实体。 MGCF/GSMC实体中的 GMSC功能根据接收到的 SRI-Ack中的被叫用户的路由信息将呼叫路由至被叫用户的拜访 VMSC后接续。
附图 4为 CS域或 网络的用户做主叫用户时， IMS域中的 CSAF采用与被叫用户当前 VMSC的 距离最近的 MGCF的承载优化策略， 且 IMS域中的 MSISDN用户做被叫用户， CS域或 PSTN网络中根 据对被叫号码的分析将呼叫路由至 IMS域并触发至 AS进行锚定的流程图。 在该流程中 , 本发明的改 进点主要在步骤 4-6〜步骤 4-9, 其它步骤与背景技术中描述的步骤基本相同。
在步骤 4-6~步骤 4-9、 具有 DTF功能的 AS接收到的被叫信息包含 DTF PSI信息的 IMRN的会话后， 对会话进行锚定控制， 即触发 B2BUA (背靠背用户代理）功能， 终止掉 AS接收到的会话， 然后发起 —个针对原被叫信息的新会话， 即具有 DTF功能的 AS通过同 HSS的 Sh接口获得被叫用户侧的 S-CSCF 信息， 然后， 将会话路由至 S-CSCF, 并由该 S-CSCF将会话路由至原被叫侧。 其中 CSRN的构成可以 是 "路由前缀 +原被叫信息 +呼叫参考号"， 这里， 路由前缀用于指示 S-CSCF能够固定寻址到某一个 MGCF。 CSAF在分配 CSRN之前， 可先向 HLR发送 ATI, 査询用户当前移动网电路交换 CS域的注册 状态， 并根据 HLR返回的 ATI Ack消息中的 Location Information信息可以判断出用户当前所在的位置 信息，然后 CSAF分配能够寻址到距离被叫用户当前移动网电路交换 CS域的 VMSC最近的 MGCF的路 由前缀。
这里， 具有 DTF功能的 AS发起一个针对原被叫信息的新会话时， 需要由具有 CSAF的 AS对原被 叫信息进行路由分析， 在具有 CSAF的 AS判断出需要将会话路由至移动网电路交换 CS域中进行接续 时， 具有 CSAF的 AS基于原被叫信息构造 TEL U I格式的 CSRN, 然后具有 DTF功能的 AS发起的针对 原被叫信息的新会话中的被叫信息 Requested-URI为 CSRN。
这里， 在 S-CSCF将呼叫路由至原被叫侧的过程中， 当原被叫信息为 TEL URI格式时， S-CSCF执 行 ENUM DNS转换功能， 如果能够将原被叫号码转换成 SIP URI格式， 则后续的呼叫路由在 MS域中 进行， 否则， S-CSCF将呼叫路由至本 IMS域的 BGCF, 由 BGCF将呼叫最终经由 MGCF路由至移动网 电路交换 CS域的 GMSC, 最后由 GMSC将呼叫接续至被叫。 在 S-CSCF将呼叫转发至 MGCF时， 当 S-CSCF根据 CRSN的路由前缀判断出需要路由的 MGCF不属于本 IMS域即用户归属的 S域时， 如用 户漫游时， 用户归属 IMS域不能覆盖到用户当前拜访的移动网电路交换 CS域， 则此时需要跨 IMS域 进行路由， 则 S-CSCF选择本 IMS域的 BGCF, 将会话路由至 BGCF, 本域的 BGCF根据路由前缀将呼 叫路由至用户拜访地的 IMS域中的 BGCF, 后续 BGCF根据路由前缀寻址到距离用户当前 VMSC最近 的 MGCF, 然后将呼叫路由至该 MGCF, 该 MGCF实体兼做 GMSC实体， 实体中的 MGCF功能向内部 的 GMSC功能发送 IAM消息。
在具有 DTF功能的 AS启用 B2BUA功能时， 对于在 DTF终止的会话和在 DTF新发起的会话， DTF 均对其维护状态， 以对后续用户可能发起的域间切换进行控制。
在步骤 4-10、 MGCF/GMSC实体中的 GMSC功能接收到 MGCF功能的入局呼叫 IAM消息后， 使用 智能网业务的方式或是其他的转换技术从中解析出原被叫用户的 MSISDN,然后 GMSC基于解析出的 MSISDN向 HLR发送 SRI消息。
上述实施例是分别根据两个不同的承载优化策略进行描述的， 其侧重点不同， 方案一侧重于减 少语音编解码的转换次数， 以保证语音业务的质量， 消除了静态锚点方案下引入的 IP承载路径对语 音质量的损耗； 方案二侧重于尽可能地延长会话的 IP承载路径， 减少 DTM承载路径， 以提高 IP承载 的利用率， 降低了网络的运营成本。 本发明也可以将上述两种技术方案结合使用， 即具有 CSAF的 AS在进行 CSRN的分配时， 可以根据运营商的偏好设置、 被叫当前在移动网电路交换 CS域的位置信 息等来确定分配的 CSRN是将会话路由回与入 IMS与呼叫相同的 MGCF还是将会话路由至能够就远 出 IMS域的 MGCF。 比如在应用本发明中的第一个方案时， 需要对 MGCF进行改动， 为了减少对现网 网元的改动， 运营商的偏好设置可以是： 本发明的方案一和方案二的结合使用方式为： 具有 CSAF 的 AS判断出接收到的 INVITE消息中的 Requested-URI为 IMRN时，采用本发明方案一进行后续的呼叫 处理， 即具有 CSAF的 AS分配的 CSRN能够将会话路由回与呼叫进入 IMS域选取的相同的 MGCF, 当 CSAF判断出接收到的 INVITE消息中的 Requested-URI为 TEL URI时， 则釆用本发明方案二进行后续 的呼叫处理， 即具有 CSAF的 AS分配的 CSRN能够将会话路由至具有被叫用户当前的 VMSC最近的 IMS域的 MGCF。
基于上述第一个核心技术内容， 本发明提供的会话路由路径控制系统如附图 5所示。
图 5中， 本发明的会话路由路径控制系统包括： 网络实体确定模块、 MS域内路由模块和跨域 路由模块。
对于需要从 IMS域路由至电路交换域的会话，网络实体确定模块主要用于确定出会话对应的 IMS 域中的网络实体。 网络实体确定模块位于本发明中的应用服务器。 网络实体确定模块可以釆用预定 承载优化策略确定 IMS域中的网络实体， 如釆用与该会话曾经路由经过的 MGCF相同的承载优化策 略、 与被叫用户当前 MSC的距离最近的 MGCF等确定 IMS域中的网络实体， 具体实现方法如上述方 法中的描述。
IMS域内路由模块主要用于获取网络实体确定模块确定的 S域中的网络实体信息，并根据该网 络实体信息将需要路由至电路交换域的会话路由至 IMS域网络实体。 IMS域内路由模块可位于 IMS域 中的 S-CSCF。 IMS域内路由模块获取 IMS域中的网络实体信息的方法有多种， 具体如上述方法中的 描述。
跨域路由模块主要用于获取需要路由至电路交换域中的网络实体信息， 并将 IMS域内路由模块 路由来的会话路由至电路交换域中的网络实体如 MSC。 域间路由模块位于 IMS域中的网络实体， 如 MGCF。
当 MGCF兼做 GMSC时，跨域路由模块的功能由 IMS域功能子模块和电路交换域功能子模块来完 成。 IMS域功能子模块接收 IMS域内路由模块转发的会话， 并将其路由至电路交换域功能子模块。 电 路交换域功能子模块： 完成对电路交换域中被叫用户的路由分析， 并根据路由分析将呼叫路由至用 户当前所在的交换中心。
本发明的第二个核心技术内容是， 当呼叫需要从电路交换域路由至 IMS域时， 如果应用服务器 能够根据预定路由策略控制会活的路由路径， 就能够实现不同的对路由优化或承载优化的目的， 如 在呼叫连续性课题下的静态锚点方案中， 如果 CS域中的 VMSC/GMSC能够将呼叫就近路由至 IMS 域的 MGCF, 则能够尽可能缩短 DTM承载路径， 减少静态锚点方案引入的对 DTM承载的影响， 优 化会话的 DTM承载路径。
根据上述本发明的第二个核心技术内容， 本发明的应用服务器为 IMS域中的具有路由控制功能 的 AS, 即具有 CSAF的 AS, 或为移动网电路交换 CS域中的具有路由控制功能的 gsmSCF, 即具有 CSAF的 gsmSCF。 IMS域中的网络实体为多个处于不同地域位置的 MGCF。 设定 IMS域中设置的 多个处于不同地域位置的 MGCF分别为 MGCF1、 MGCF2、 MGCF3、 MGCF4, 如附图 6所示。
首先， 移动网电路交换 CS域中的呼叫由 MSC根据预定触发机制触发至应用服务器时， 应用服 务器能够根据 MSC对呼叫触发携带的信息确定出 MSC的位置信息， 即主叫用户当前的位置信息， 这样， 应用服务器就能够根据预定策略确定出需要将该呼叫路由至 IMS域中的某个 MGCF的信息， 如应用服务器设定就近路由策略， 则应用服务器根据就近路由策略确定出距离该 MSC位置最近的 IMS域中的 MGCF的信息， 然后应用服务器向 MSC提供该 MGCF的路由信息， 使得 MSC能够根 据获得的路由信息将呼叫从指定的 MGCF就近路由至 IMS域。对应于图 6中，应用服务器确定出距 离移动网电路交换 CS域中的 VMSC最近的 MGCF信息， 即 MGCF4信息，然后向 VMSC提供包含 MGCF4路由前缀的 IMRN4作为新的被叫信息。在 VMSC对获得的新的被叫信息进行分析时， 则可 以根据 RN4中包含的 MGCF4路由前缀信息将呼叫路由至 MGCF4。 从图 6中可明显看出， 本发 明有效缩短了移动网电路交换 CS域与 IMS域之间的 DTF承载的距离， 优化了 DTM承载路由。
上述的应用服务器向 MSC提供 MGCF 路由信息的方式有多种， 如由应用服务器直接将包含
MGCF路由前缀的 IMRN作为新的被叫信息提供给 MSC。 又如由应用服务器将包含 MGCF路由前 缀的 IMRN提供给 UE， 由 UE在发起呼叫时将 IMRN作为被叫信息携带给 MSC。
上述的应用服务器向 MSC提供 MGCF路由信息时，可以提供本 IMS域中能够路由至本 IMS域， 即被叫信息 DTF PSI归属的 IMS域中 MGCF的路由信息， 在能够获得其他 IMS域的 MGCF的位置 信息以及相应的路由信息时， 如根据 MSC位置信息判断出 MSC距离其他 IMS域中的某个 MGCF 最近， 则应用服务器也可以提供能够路由至其他 IMS域， 即非被叫信息 （DTF PSI) 归属的 MS域 中 MGCF的路由信息。当移动网电路交换 CS域的呼叫路由至其他 IMS域中的 MGCF后， 由于其他 MS域中的 MGCF不能确定非本 IMS域中的被叫信息（DTF PSI)的域名， 因此 MGCF需要对被叫 信息进行 ENUM DNS转换， 将 TEL URI格式的 DTF PSI转换成 SIP URI后， 根据 SIP URI的域名 信息确定出该 DTF PSI归属 IMS域中 I-CSCF的地址信息， 然后将呼叫路由至该 I-CSCF。
本发明中移动网电路交换 CS域的呼叫可以为移动网电路交换 CS域中主叫侧发起的初始呼叫， 也可以为移动网电路交换 CS域中被叫侧发起的初始呼叫， 相应的 MSC可以为 VMSC或 GMSC, 且 MSC的预定触发机制也包括多种， 如 CAMEL机制、 USSD机制、 Notify机制以及信令拦截机制 等， 下面结合附图 1、 附图 2对本发明的第二个核心技术内容应用于 CAMEL机制的处理进行详细 描述。
图 1中， 移动网电路交换 CS域的主叫用户的 VMSC将该主叫用户的呼叫通过 CAMEL机制触 发到移动网电路交换 CS域中具有 CSAF的 gsmSCF时， 其触发的是移动网电路交换 CS域主叫侧 CAMEL签约信息。 '
在步骤 1-3中， 具有 CSAF的 gsmSCF通过接收到的 CAMEL消息 IDP ( Initial Detected Point初 始检出点） 中的触发的检出点为 DP2获知本次 CAMEL交互是一个针对主叫侧用户的发起的呼叫的 交互， 并可根据 IDP消息中的 MSC地址信息判断出移动网电路交换 CS域主叫用户的当前所在的 VMSC的位置信息， 然后根据网络数据配置信息， 如不同的 MGCF和 VMSC所在的地理位置信息， 确定出主叫用户当前所在的 VMSC距离 MGCF4最近。 则具有 CSAF的 gsmSCF在分配 IMRN时， 分配的 IMRN中应包含有 MGCF4的路由信息，使得 VMSC能够根据该 IMRN将呼叫路由至 MGCF4。 这里， 如果将包含有 MGCF4路由信息的 IMRN称为 IMRN4, 则 IMRN4的构造可以为： MGCF4路 由前缀 +DTF PSI+呼叫参考号。 当然， 本发明不限制 MGCF4路由信息在 IMRN中的位置。 然后， 具有 CSAF的 gsmSCF将 IMR 4作为新的被叫信息通过 CAMEL connect操作下发至移动网电路交 换 CS域中主叫用户当前所在的 VMSC。
这样， 在步骤 1-4中， VMSC对接收到的新的被叫信息进行分析时， 就能够根据 IMRN4中包含 的 MGCF4路由信息将呼叫路由至与其距离最近的 MGCF4中。从而，减少了静态锚点的呼叫控制方 案引入的 DTM承载迂回路径。
当 IMRN的构成为" MGCF路由前缀 +DTF PSI+呼叫参考号"的方式时,使 VMSC接收到 CAMEL connect操作中的 IMRN,对接收到的新的被叫信息进行分析时，通过对 IMRN中包含的 MGCF的路 由信息的分析就能将呼叫路由至相应的 MGCF, 而 MGCF可以去除 IMRN中包含的 MGCF的路由 信息， 如扣除 IMRN路由前缀， 将 IMRN恢复成 "DTF PSI+呼叫参考号"的方式， 这样， 后续过程中 呼叫都将按照现有技术中的描述进行处理， 如背景技术图 1中的步骤 1-5至步骤 1-7， 不会影响到其 他实体的相关处理。
图 2中，对于移动网电路交换 CS域的用户作被叫， 当呼叫路由至被叫用户的归属移动网电路交 换 CS域中的 GMSC时， GMSC使用 CAMEL机制将接收到来自于主叫侧的呼叫触发至移动网电路 交换 CS域中具有 DRF功能的 gsmSCF时， 这里触发的是被叫侧 CAMEL签约信息。 在步骤 2-6, 具有 DRF功能的 gsmSCF生成一个指向 IMS域中的具有 DTF功能的一个 AS的路 由号码 IMRN (IMS Routing Number) ， 使得 GMSC根据该路由号码将呼叫路由至该 DTF上。 在具 有 DRF功能的 gsmSCF分配 IMRN时， 需要根据当前将移动网电路交换 CS域呼叫触发至移动网电 路交换 CS域中具有 DRF功能的 gsmSCF的 GMSC位置信息进行分配，如具有 DR 功能的 gsmSCF 根据步骤 2-3中接收到的 CAMEL消息 IDP中的触发检出点为 DP12获知本次 CAMEL交互是一个 被叫侧用户的交互，并可根据 IMP消息中的 MSC地址信息判断出移动网电路交换 CS域被叫用户归 属网络中 GMSC的位置信息， 然后确定出被叫用户归属网络中的 GMSC距离 MGCF4最近。则具有 DRF功能的 gsmSCF在分配 IMRN时， 分配的 RN中应包含有 MGCF4的路由信息， 使得 GMSC 能够根据该 IMRN将呼叫路由至 MGCF4。 这里， 如果将包含有 MGCF4路由信息的 IMRN称为 IMRN4, 则 IMRN4的构造可以为： MGCF4路由前缀 +DTF PSI+呼叫参考号。 当然， 本发明不限制 MGCF4路由信息在 IMRN中的位置。 然后， 具有 DRF功能的 gsmSCF将 IMRN4作为新的被叫信 息通过 CAMEL connect操作下发至移动网电路交换 CS域中被叫用户归属的 GMSC。
这样， 在步骤 2-7中， GMSC对接收到的新的被叫信息进行分析时， 就能够根据 IMRN4中包含 的 MGCF4路由信息将呼叫路由至与其距离最近的 MGCF4中。从而，减少了静 锚点的呼叫控制方 案引入的 DTM承载迂回路径。
后续 IMS域中的 MGCF的处理同图 1中的处理过程。
本发明的第二个核心技术内容也可以应用于 USSD机制、 Notify机制、 信令拦截机制等， 其实 现的核心技术内容都是相同的， 只是在具体的信令名称、 网络实体上略有区别， 在此不再详细描述。
基于上述第二个核心技术内容， 本发明提供的路由路径控制系统如附图 7所示。
图 7中， 路由路径控制系统包括： IMS域网络实体确定模块和路由模块。
IMS域网络实体确定模块： 对于需要从电路交换域路由至 IMS域的呼叫， IMS域网络实体确定模 块根据预定策略确定出呼叫需路由至的对应的 IMS域中的网络实体信息，该 IMS域中的网络实体可以 为： MGCF。 IMS域网络实体确定模块可分别根据电路交换域中主叫侧发起的初始呼叫、 电路交换域 中被叫侧发起的初始呼叫以及不同的呼叫触发方式等采用相应的方法来确定 IMS域网络实体信息， 进一步的， IMS域网络实体确定模块将确定的 IMS域网络实体信息提供给路由模块。具体过程如上述 方法中的描述， 在此不再详细描述。 MS域网络实体确定模块可位于 IMS域的 AS中， 如位于 IMS域的 具有 CSAF的 AS中， 也可位于电路交换域中的实体中， 如移动网电路交换 CS域的 gsmSCF中。
路由模块： 根据 IMS域网络实体确定模块提供的 IMS域网络实体信息， 将呼叫路由至 IMS域中相 应的实体， 如相应的 MGCF。 IMS域网络实体确定模块向路由模块提供 IMS域网络实体信息的方法有 多种， 如通过 CAMEL connect操作被叫信息参数， 或是 SRI-Ack消息中 MSRN参数来携带 IMS域网络 实体信息。 具体过程如上述方法中的描述， 在此不再详细描述。
路由模块可位于电路交换域中的实体中， 如位于移动网电路交换 CS域中的交换中心如 VMSC或 GMSC中等。 '
虽然通过实施例描绘了本发明， 本领域普通技术人员知道， 本发明有许多变形和变化而不脱离 本发明的精神， 本发明的申请文件的权利要求包括这些变形和变化。

Claims

权利要求
1、 一种会话路由路径控制方法， 其特征在于， 对于需要从 IP多媒体子系统 IMS域路由至电路 交换域的会话， 该方法包括以下步骤- a、 应用服务器确定出所述会话对应的 IMS域中的网络实体；
b、应用服务器向服务呼叫会话控制功能 S-CSCF提供其确定的所述 IMS域中的网络实体信息， 并 由 S-CSCF将所述会话路由至所述 IMS域中的网络实体；
c、 所述 IMS域中的网络实体将所述会话路由至电路交换域中的网络实体。
2、 如权利要求 1所述的方法， 其特征在于， 所述电路交换域为： 移动网络的电路交换 CS域， 或公众电话交换网 PSTN的 CS域。
3、 如权利要求 2所述的方法， 其特征在于， 所述步骤 a具体包括：
应用服务器根据预定承载优化策略确定出所述会话对应的 IMS域中的网络实体。
4、 如权利要求 2所述的方法， 其特征在于， 所述需要从 IMS域路由至电路交换域的呼叫包括： 被叫为电路交换域用户时，在 IMS域中发起的主叫侧会话， 或需要在 IMS域中进行锚定过程的电路 交换域的被叫侧初始呼叫。
5、 如权利要求 3所述的方法， 其特征在于， 所述步骤 a中预定承载优化策略为： 与该会话曾经 路由经过的媒体网关控制功能 MGCF相同； 且所述步骤 a具体包括：
al、 应用服务器获取所述会话对应的呼叫在从电路交换域路由至 IMS域时经过的 MGCF; a2、 应用服务器将该 MGCF确定为所述会话对应的 IMS域中的网络实体信息。
6、 如权利要求 5所述的方法， 其特征在于， 所述步骤 al中： 呼叫在从电路交换域路由至 IMS 域时经过的 MGCF是由应用服务器根据预定策略确定的。
7、 如权利要求 6所述的方法， 其特征在于， 步骤' al中的预定策略包括： 预定就近路由策略。
8、 如权利要求 5所述的一种会话路由路径控制方法， 其特征在于， 所述步骤 al具体包括： al2、 MGCF将其信息承载于邀请 INVITE消息中，并通过 S-CSCF将该消息传输至应用服务器； al3、 应用服务器将 INVITE消息中携带的 MGCF的信息确定为需要路由至 CS域的会话曾经路 由经过的 MGCF的信息。
9、 如权利要求 8所述的方法， 其特征在于， 所述步骤 al2的 INVITE消息中还包括： MGCF为 该会话分配呼叫参考号， 该呼叫参考号用于标识会话。
10、 如权利要求 6、 7或 8所述的方法， 其特征在于， 所述步骤 b具体包括：
应用服务器根据所述 MGCF信息构造 CS域路由号码 CSRN, 并将其下发至 S-CSCF;
S-CSCF根据所述 CSRN中的 MGCF信息将所述会话路由至该 MGCF。
11、如权利要求 10所述的方法，其特征在于：所述 CSRN包括： MGCF路由信息和原被叫信息； 或者所述 CSRN包括： MGCF路由信息和原被叫信息和呼叫参考号。
12、 如权利要求 11所述的方法， 其特征在于， 所述步骤 c还包括：
MGCF获取 S-CSCF转发的会话的呼叫参考号， 并根据该呼叫参考号确定该会话为曾经路由过 的会话时， 控制媒体网关功能 MGW不对出呼和入呼的会话进行编解码转换。
13、 如权利要求 3所述的方法， 其特征在于， 所述步骤 a中预定承载优化策略为： 与被叫用户 当前 MSC的距离最近的 MGCF; 且所述步骤 a具体包括：
应用服务器获取需要路由至移动网电路交换 CS域的会话的被叫用户当前位置信息,并根据该位 置信息确定与被叫用户当前拜访移动交换中心 VMSC距离最近的 MGCF信息。
14、 如权利要求 13所述的方法， 其特征在于， 所述步骤 b具体包括：
应用服务器根据所述 MGCF信息构造 CSRN, 并将其下发至 S-CSCF;
S-CSCF根据 MGCF信息确定所述需要路由至电路交换域的会话需要进行跨 S域路由时，将该 会话通过其所在的 MS域的边界网关控制功能 BGCF、 用户拜访地的 BGCF, 路由至所述 MGCF。
15、 如权利要求 13所述的方法， 其特征在于， 所述步骤 c具体包括：
兼做关口移动交换中心 GMSC的 MGCF从归属位置寄存器 HLR处获取移动网电路交换 CS域被 叫用户的路由信息， 并根据所述路由信息将该会话直接路由至被叫用户当前所在的 MSC。
16、 如权利要求 3所述的方法， 其特征在于， 步骤 a中的预定承载优化策略包括： 与该会话曾 经路由经过的 MGCF相同或与被叫用户当前 MSC的距离最近的 MGCF; 且所述步骤 a具体包括： 应用服务器根据预定规则选取一种预定承载优化策略，并根据选取的承载优化策略确定需要路 由至电路交换域的会话对应的 IMS域中的网络实体。
17、如权利要求 16所述的方法，其特征在于， 所述步骤 a中的 IMS域中的应用服务器根揭预定 规则选取一种预定承载优化策略的步骤具体包括- 应用服务器根据用户偏好设置选取一种预定承载优化策略； 和 /或
应用服务器根据被叫用户在电路交换域的位置信息选取一种预定承载优化策略。
18、 如权利要求 16所述的方法， 其特征在于， 所述用户偏好设置具体包括：
在应用服务器接收到的 INVITE消息中承载有 IMRN时， 选取与该会话曾经路由经过的 MGCF 相同的承载优化策略；
在应用服务器接收到的 INVITE消息中承载有使用电话号码描述的资源定位标识 Tel URI时，选 取与被叫用户当前 MSC的距离最近的 MGCF的承载优化策略。
19、 如权利要求 1所述的方法， 其特征在于， 所述应用服务器为： IMS域中具有域间路由功能 的应用服务器。
20、 一种会话路由路径控制系统， 其特征在于， 包括：
位于应用服务器的网络实体确定模块： 对于需要从 IMS域路由至电路交换域的会话， 确定出会 话对应的 IMS域中的网络实体；
位于 IMS域中的 IMS域内路由模块： 获取网络实体确定模块确定的所述 MS域中的网络实体信 息， 并根据所述网络实体信息将所述需要路由至电路交换域的会话路由至 MS域网络实体；
位于 IMS域网络实体中的跨域路由模块： 获取需要路由至电路交换域中的网络实体信息， 并将 所述 MS域内路由模块转发的会话路由至电路交换域中的网络实体。
21、 根据权利要求 20所述的系统， 其特征在于， 位于 IMS域中的网络实体的跨域路由模块进一 步包括： IMS域功能子模块： 接收 IMS域内路由模块转发的会话， 并将其路由至电路交换域功能子模块； 电路交换域功能子模块： 对电路交换域中被叫用户的路由进行分析， 并根据路由分析将会话路 由至被叫用户当前所在的交换中心。
22、 一种路由路径控制方法， 其特征在于， 对于需要从电路交换域路由至 MS域的呼叫， 该方 法包括以下步骤：
a、 应用服务器确定出所述呼叫对应的 S域中的网络实体；
b、 应用服务器向电路交换域中的网络实体提供其确定的所述 IMS域中的网络实体信息； c、 所述电路交换域中的网络实体将所述呼叫路由至所述 IMS域中的网络实体。
23、 如权利要求 22所述的一种路由路径控制方法， 其特征在于， 所述需要从电路交换域路由至 IMS域的呼叫包括： 需要在 IMS域中进行锚定过程的电路交换域的呼叫。
24、 如权利要求 23所述的一种路由路径控制方法， 其特征在于， 所述应用服务器为： IMS域中 具有域间路由功能的应用服务器， 或移动网电路交换 CS域中具有域间路由功能的 gsm业务控制功 能 gsmSCF, 或具有域间路由功能的信令转发功能 SRF。
25、 如权利要求 22、 23或 24所述的一种路由路径控制方法， 其特征在于， 所述步骤 a进一步 包括：
al、 移动网电路交换 CS域中的发起初始呼叫的 MSC根据预定触发机制将该呼叫触发至所述应 用服务器；
a2、 所述应用服务器根据预定策略确定出需要将该呼叫路由至 IMS域中的 MGCF的信息。
26、 如权利要求 25所述的一种路由路径控制方法， 其特征在于- 所述移动网电路交换 CS域中的发起初始呼叫为： 主叫侧为 CS域时， VMSC接收到用户设备
UE的呼叫建立消息后发起的呼叫、 或被叫侧为 CS域时， GMSC在接收到来自于主叫侧的呼叫后， 对被叫信息分析后发起的呼叫；
所述预定触发机制为： 移动网络增强逻辑用户应用 CAMEL机制、 或无结构化补充业务数据 USSD机制、 或通知 Notify机制、 或信令拦截机制。
27、 如权利要求 26所述的一种路由路径控制方法， 其特征在于， 所述步骤 a2具体包括： 所述应用服务器获取移动网电路交换 CS域中主叫侧 VMSC的位置信息， 并根据就近策略确定 出距离所述 VMSC最近的 MGCF; 或
所述应用服务器获取移动网电路交换 CS域中主叫用户当前的位置信息，并根据就近策略确定出 距离所述主叫用户当前的 VMSC最近的 MGCF; 或
所述应用服务器获取移动网电路交换 CS域中被叫侧 GMSC的位置信息， 并根据预定就近策略 确定所述 GMSC对应的 MGCF。
28、如权利要求 27所述的一种路由路径控制方法， 其特征在于， 所述应用服务器获取移动网电 路交换 CS域中主叫侧 VMSC位置信息的步骤包括：
所述应用服务器根据 CAMEL初始检测点 IDP消息中携带的 MSC地址信息确定 CS域中主叫侧 VMSC的位置信息。
29、 如权利要求 27所述的一种路由路径控制方法， 其特征在于， 所述应用服务器获取移动网电 路交换 CS域中被叫恻 GMSC位置信息的步骤包括：
所述应用服务器根据 CAMEL IDP消息中携带的 MSC地址信息确定移动网电路交换 CS域中被 叫侧 GMSC的位置信息； 或
所述应用服务器根据发送路由信息 SRI消息中携带的 MSC地址信息确定移动网电路交换 CS域 中被叫侧 GMSC的位置信息。
30、 如权利要求 27所述的一种路由路径控制方法， 其特征在于， 所述步骤 b具体包括： 所述应用服务器根据所述 MGCF信息构造 IMS域路由号码 IMRN,并将其下发至 VMSC/GMSC; 或
所述应用服务器根据所述 MGCF信息构造 IMRN,并将其下发至 UE, 所述 UE在发起呼叫时将 所述 IMRN提供给其当前所在的 VMSC。
31、 如权利要求 30所述的一种路由路径控制方法， 其特征在于：
所述 IMRN包括： MGCF路由信息和域间转移功能公共业务标识 DTF PSI和呼叫参考号码； 或 所述 IMRN包括： MGCF路由信息和 DTF PSL
32、 如权利要求 22所述的一种路由路径控制方法， 其特征在于， 所述步骤 a还包括： 当应用服务器确定出的 IMS域中的网络实体 MGCF不属于本归属 IMS域中的网络实体时， MGCF通过对被叫信息进行 E.164域名转换系统 ENUM DNS转换功能来确定出归属 IMS域中的查 询 CSCF I-CSCF地址信息。
33、 一种路由路径控制系统， 其特征在于， 包括：
位于应用服务器的 IMS域网络实体确定模块：对于需要从电路交换域路由至 IMS域的呼叫，根据 预定策略确定出呼叫需路由至 IMS域中的网络实体， 并将所述 MS域网络实体信息提供给路由模块； 位于电路交换域的路由模块： 根据 S域网络实体确定模块提供的 IMS域陶络实体信息， 将呼叫 路由至 IMS域中相应的实体。
34、 一种应用服务器， 其特征在于， 所述应用服务器中设置有 IMS域网络实体确定模块， 对于 需要从电路交换域路由至 IMS域的呼叫，所述 IMS域网络实体确定模块根据预定策略确定出呼叫需 要路由至的 IMS域中的网络实体，并将所述 IMS域中的网络实体信息提供给电路交换域中的网络实 体。
35、 一种交换中心， 设置于电路交换域中， 其特征在于， 所述交换中心中设置有路由模块， 所 述路由模块根据应用服务器提供的 IMS域网络实体信息， 将呼叫路由至 IMS域中相应的网络实体。
PCT/CN2006/001953 2005-08-08 2006-08-03 Procédé et système de commande d'un trajet d'acheminement de session WO2007016863A1 (fr)

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CN2005100898345A CN1913504B (zh) 2005-08-08 2005-08-08 一种路由路径控制方法、系统和装置
CN200510089833.0 2005-08-08
CN200510089833A CN100583843C (zh) 2005-08-08 2005-08-08 一种会话路由路径控制方法和系统
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WO2005025196A1 (en) * 2003-09-11 2005-03-17 Nokia Corporation Ip-based services for circuit-switched networks
WO2005027460A1 (en) * 2003-09-12 2005-03-24 Telefonaktiebolaget Lm Ericsson (Publ) Combinational multimedia services

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Publication number Priority date Publication date Assignee Title
WO2002104057A1 (en) * 2001-06-18 2002-12-27 Nokia Corporation Roaming from ims domain to the cs domain
WO2004073279A1 (en) * 2003-02-15 2004-08-26 Telefonaktiebolaget Lm Ericsson (Publ) Conversational bearer negotiation
WO2005025196A1 (en) * 2003-09-11 2005-03-17 Nokia Corporation Ip-based services for circuit-switched networks
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