METHOD, APPARATUS AND SYSTEM FOR FALLING BACK VOICE CALL TO CIRCUIT SWITCHING DOMAIN

摘要

A method for falling back a voice call to circuit switching (CS) domain is disclosed by the present invention, which includes: receiving a service request message sent by a calling User Equipment (UE), which includes the called number information of the voice call in CS domain; instructing an Evolved NodeB (ENB) to start the Circuit Switching Fall-Back (CSFB) handover; receiving a handover request message sent by the ENB, which includes the required information for CS handover; selecting a Mobile Switching Center (MSC) and sending a Packet Switching (PS) to CS handover request message to the MSC, which includes the required information for CS handover and the called number, so that the MSC calls the called UE; receiving a PS to CS handover response message returned by the MSC, which includes the information of the CS resources prepared by the target Base Station Subsystem (BSS)/Radio Network Subsystem (RNS); sending a handover command message to the calling UE via the ENB, which includes the information of the CS resources prepared by the target BSS/RNS, so that the calling UE accesses into 2G/3G network. The corresponding apparatus and system are also provided. The solution of the present invention can reduce the connection delay.