Patent ID: 8730917

Claim:
A method for realizing single radio voice call continuity which is applied in IP Multimedia Core Network Subsystem (IMS) network, the method comprising: receiving, by a Service Continuity Application Server (SC AS), a handover request, and then updating, by the SC AS, a remote leg, and transmitting, by the SC AS, a handover notification message to a user terminal; receiving, by the user terminal, a handover command in a Packet Switch (PS) domain and the handover notification message, then adjusting, by the user terminal, an access mode to be accessing a Circuit Switch (CS) domain, wherein the SC AS receiving the handover request and then updating the remote leg and transmitting the handover notification message to the user terminal comprises: transmitting, by the SC AS, a message requesting for initiating update to the remote leg after the SC AS receives the handover request; receiving, by the SC AS, an update request message transmitted from the remote leg, then transmitting, by the SC AS, an update agreement message to the remote leg, and transmitting, by the SC AS, the handover notification message to the user terminal after waiting for a period of time; wherein the waiting period of time does not exceed a difference between a time period for transmitting the update agreement message to the remote leg and a time period for transmitting the handover notification message to the user terminal.