System and method for indicating circuit switched access at IMS registration

摘要

In IP Multimedia Subsystem (IMS) IMS Control Channel Protocol (ICCP) is used between a user equipment (UE) and IMS Control Channel Function (ICCF) and Session Initiated Protocol (SIP) interface (between to ICCF, Call Session Control Function and Application Server) to support the indication of Circuit Switched (CS) access utilizing P-Access-Network-Information header. The indication can be used by an S-CSCF or AS for different purposes such as routing decision, charging, and presence info.