Patent ID: 8929223
Filing Date: 2015-01-06
Classification: H04L,H04W

Abstract:
1. A system to control a Voice over Internet Protocol (VoIP) service, comprising: a user terminal to receive a first mobile IP allocated by a wireless packet network and a second mobile IP allocated by a wireless local area network (LAN), the first mobile IP to be used in an always-on function; a first Proxy-Call Session Control Function (P-CSCF), through which the user terminal performs a first registration procedure in order to receive the VoIP service over the wireless LAN; a second P-CSCF, through which the user terminal performs a second registration procedure in order to receive the VoIP service over the wireless packet network; and a CSCF to control a VoIP call based on a Session Initiation Protocol (SIP), wherein the user terminal performs the first registration procedure through the first P-CSCF using the second mobile IP, monitors a signal intensity of the wireless LAN while receiving the VoIP service over the wireless LAN, and performs the second registration procedure through the second P-CSCF using the first mobile IP if the signal intensity of the wireless LAN is weaker than a first reference value, and wherein if the user terminal performs the second registration procedure using the first mobile IP after performing the first registration procedure using the second mobile IP, the CSCF determines that a SIP session of the first mobile IP is a currently-used session and sends an incoming VoIP call for the user terminal to the second P-CSCF.