Patent ID: 8725148
Filing Date: 2014-05-13
Classification: H04L,H04M,H04W

Abstract:
1. A method of handing off an active call at a Voice-over-IP (VoIP) interface of a client dual-mode device to a cellular interface of the dual-mode device, the active call including a VoIP leg from the dual-mode device to a first termination point, the first termination point including a private branch exchange (PBX), the method comprising: receiving, at a communications server via an Internet Protocol (IP) IP network, a handoff message from the VoIP interface of the dual-mode device, wherein said handoff message comprises a custom session initiation protocol (SIP) message containing a handoff feature indicator and containing a cellular interface number for the dual-mode device and a call identifier regarding the active call; initiating a cellular call, via the PBX over a public land mobile network (PLMN), from the communications server to the cellular interface of the dual-mode device; receiving, at the communications server, a ringing message from the PBX; sending in response to receiving the custom SIP message, while the cellular interface of the dual-mode device is ringing, an SIP 200 OK message from the communications server via the IP network to the dual-mode device confirming that the ringing of the initiated cellular call for the dual-mode device is for handoff of the active call from the VoIP interface to the cellular interface, the dual-mode device responsive to the SIP 200 OK message by automatically accepting the initiated cellular call in response to receiving the SIP 200 OK message and not accepting any other cellular calls; receiving an accept message via the PLMN with regard to the initiated cellular call, the accept message confirming connection of the cellular call with the cellular interface of the dual-mode device; and, terminating the VoIP leg.