SERVICE REALIZATION METHOD AND SYSTEM FOR IP MULTIMEDIA SUB-SYSTEM (IMS) NETWORK, AND ENHANCED MOBILE SWITCHING CENTER

摘要

A service realization method of IP Multimedia Sub-system (IMS) network is provided. The method includes: after receiving a request for providing a roaming number carrying a User Equipment (UE) number sent by a home network of the UE, an Enhanced Mobile Switching Center (E-MSC) returns the roaming number corresponding to the number of the UE and pointing to the E-MSC to the home network of the UE; after receiving an initial address message carrying the roaming number sent by the Public Switched Telephone Network (PSTN) on which a calling user locates, the E-MSC takes the number of the UE as a called number, and sends a session invitation message to the PSTN via the Serving Call Session Control Function (S-CSCF) entity and the Proxy Call Session Control Function (P-CSCF) entity; after receiving a ringing message of Session Initial Protocol (SIP) sent by the UE, the E-MSC sends an address finish message to the PSTN; and after receiving an answer message of SIP sent by the UE, the E-MSC connects the IP media bearing between the E-MSC and the UE with the CS media bearing between the E-MSC and the PSTN, and sends the answer message of circuit domain to the PSTN, consequently accomplishes the establishment of the IMS session service.