Patent ID: 8879544

Claim:
A method of establishing a call between a hybrid mobile device and a target communication device mediated by an IP network based call server, the method comprising: in the call server: receiving a communication session establishment message from the hybrid mobile device, the hybrid mobile device having an associated VoIP telephone number and an associated cellular telephone number, the message indicative of the hybrid mobile device wanting to place a call to the target communication device, the target communication device having an associated target telephone number, the communication session establishment message including information pertaining to the VoIP telephone number, the cellular telephone number, the target telephone number, and a connection status indicator, the connection status indicator indicative of whether the hybrid mobile device has an IP connection with an IP access point sufficient to support VoIP telephony; determining whether the hybrid mobile device is currently connected to an IP network access point; establishing a first communication link between the call server and the hybrid mobile device using the VoIP telephone number over a packet data network when the connection status indicator for the hybrid mobile device is sufficient; establishing a first communication link between the call server and the hybrid mobile device using the cellular telephone number over a cellular network when the connection status indicator for the hybrid mobile device is insufficient; establishing a second communication link between the call server and the target communication device using the target telephone number; and joining the first and second communication links to establish a communication session between the hybrid mobile device and the target communication device.