Patent ID: 8582566

Claim:
A method for transferring capability information of a calling-party User Equipment (UE) in combined Circuit-Switched (CS) and Internet Protocol Multimedia Subsystem (IMS) services (CSI), the method comprising: receiving, by a CSI Application Server (AS), a first Session Initiation Protocol (SIP) request message originating from the calling-party UE; generating, by the CSI AS, a second SIP message containing the capability information of the calling-party UE; and transmitting, by the CSI AS, the second SIP message containing the capability information of the calling-party UE to a called-party UE in a CS domain, wherein the capability information of the calling-party UE comprises i) information representing if the calling-party UE is capable of simultaneous CS and Packet-Switched (PS) services, ii) IMS state information representing if the calling-party UE is IMS registered, iii) version information representing if the capability information is updated, and iv) a personal Mobile Equipment (ME) identifier of the calling-party.