Patent ID: 8880126

Claim:
A method for a power-efficient communication device having a wireless local area network (WLAN) interface for connecting to a WLAN and a cellular interface for connecting to a cellular network, the WLAN interface and the cellular interface each being capable of communicating using the Session Initiation Protocol (SIP), the method comprising: receiving a first status update from the communication device at a first SIP server serving the WLAN interface, the first status update indicating that the WLAN interface is deactivated; relaying a first SIP INVITE message received at the first SIP server to a second SIP server serving the cellular interface in response to the indication that the communication device is deactivated; receiving a second status update from the communication device at the first SIP server, the second status update indicating that the WLAN interface is activated; and forwarding a second SIP INVITE message received at the first SIP server directly through the WLAN to the WLAN interface in response to the indication that the WLAN interface is activated.