Patent ID: 9380496
Filing Date: 2016-06-28
CPC Classification: H04W

Claim Text:
1. A method comprising: detecting or establishing a circuit-switched call over a cellular network; establishing, over a cellular network, a voice-over-internet-protocol standby call in parallel to the circuit-switched call, wherein the voice-over-internet-protocol standby call is a standby, virtual call that includes an established end-to-end signaling path but utilizes no physical radio resources, wherein the end-to-end signaling path is ready for use after a cellular handover situation to an active voice-over-internet protocol call established using the end-to-end signaling path; detecting the cellular handover situation; when the detected cellular handover situation is to a first type of network: when the detected cellular handover situation is to a second type of network, wherein the second type of network is different from the first type of network: