Patent attributes
A method of setting up a session between peer user terminals of a communication system, wherein at least one of the user terminals is a dual-mode terminal having access to both an IP-based packet-switched access network and a circuit-switched access network, and the session extends at least in part across the circuit-switched access network. One of the user terminals initiates the session by sending Session Initiation Protocol (SIP) signaling to a SIP server over the IP-based network. The SIP server sends a notification to a gateway server to establish one or more conversational bearers. The gateway server then sends a callback telephone number to the dual-mode terminal. The dual-mode terminal then calls the callback number to establish a circuit-switched session with the gateway server.
