Patent ID: 7852815

Claim:
A method for handing off an in-progress call in a communications system that comprises a wireless wide area network (WAN) and a wireless local area network (WLAN) having at least partially overlapping coverage areas, a mobile device having a WAN communications subsystem for exchanging wireless voice data with the WAN and a WLAN communications subsystem for exchanging wireless voice data with the WLAN, wherein prior to handoff a communications path between the mobile device and a remote location comprises a first voice path through one of the WAN and the WLAN, the handoff method comprising: establishing a second voice path between the mobile device and the remote location through the other one of the WAN and the WLAN; transmitting in parallel streams of identical voice data over the first and second voice paths; comparing the streams of voice data after they have been transmitted through the first and second voice paths to determine a differential delay in transmission times between the first and second paths; and synchronizing the parallel streams of voice data based on the determined differential delay and then terminating the first voice path, wherein synchronizing the parallel streams comprises increasing or decreasing a duration of the voice data transmitted over the first path by adding time to or cutting time from, respectively, quiet intervals in the voice data.