Method for connecting calls between an IP multimedia subsystem (IMS) domain and a circuit switched (CS) domain

摘要

A call connection method is provided. When a terminal is in an IMS unregistered state, information indicating whether to perform a session transfer toward a CS domain is stored in a server during a registration or deregistration process. When receiving a call connection request message over an IMS, if the terminal is in the IMS unregistered state and the information indicates the session transfer, the call transfer toward the CS domain can be performed.