Patent ID: 8238919

Claim:
A method of operating a dual mode mobile terminal comprising a wireless local area network interface and a cellular radio interface, comprising the steps of: camping on the cellular radio interface when idle; if wireless local area network coverage is possible from an access point providing wireless local area network telephony calls, but no transmission is active over the access point, entering a power save mode by switching off the wireless local area network interface; when receiving a Page Request message over the cellular radio interface indicating an incoming voice call over the cellular radio interface, performing a determination as to whether wireless local area network coverage is possible from an access point providing wireless local area network telephony calls and, if so: responding, by issuing a wireless local area network call message to the wireless local area network access point thus determined over the wireless local area network interface to an interworking node; subsequently engaging in a call initiation procedure, an assign traffic channel procedure and a call confirmation and call accepted procedure with the interworking node; and, processing the incoming voice call over the wireless local area network interface towards another party, wherein when the call is ended, the dual mode mobile terminal going back to camp on the cellular radio interface.