EMERGENCY CALL SERVICE REALIZING METHOD AND P-CSCF FOR IP MULTIMEDIA SUBSYSTEM

摘要

An emergency call service realizing method for IP Multimedia Subsystem, the method comprises that Proxy Call Session Control Function (P-CSCF) detects the call attribute and determines the call type and the session type after receiving the call session invitation request started by a user equipment; if the P-CSCF determines that the call is an emergent call and is an IP Multimedia Subsystem Centralized Service (ICS) session, an alternative service response containing an emergency call indication is fed back to the user equipment, and the user equipment is notified that the call is an emergency call; a new emergency call is started from an IPMultimedia Subsystem (IMS) domain or circuit domain after the user equipment receives the alternative service response.