Patent ID: 8504043
Filing Date: 2013-08-06
Classification: H04W

Abstract:
1. A method for voice call fallback to a circuit switched (CS) domain, comprising: sending, by a mobility management entity (MME), a Location Update message including an identity of a called user equipment (UE) to a mobile switching center (MSC) to make the MSC create an association with the MME and complete a location update procedure of a CS domain; sending, by the MME, a first CS Paging Request message to the called UE through an evolved NodeB (eNB) when receiving a second CS Paging Request message from the MSC; receiving, by the MME, a Service Request message from the called UE, determining that the called UE accepts the call, and instructing the eNB to initiate circuit switched fallback (CSFB) handover; receiving, by the MME, a first Handover Request message from the eNB, wherein the first Handover Request message comprises first information required for CS handover, selecting the MSC and directly sending a packet switched (PS) to CS Handover Request message to the MSC, wherein the PS to CS Handover Request message comprises second information required for CS handover; and receiving, by the MME, a PS to CS Handover Response message returned by the MSC, wherein the PS to CS Handover Response message comprises CS resource information prepared by a target base station subsystem/radio network subsystem (BSS/RNS), and sending a Handover Command message to the called UE through the eNB, wherein the Handover Command message comprises the CS resource information prepared by the target BSS/RNS so that the called UE accesses a 2nd generation/3rd generation (2G/3G) network, wherein if the 2G/3G network supports PS handover, the first Handover Request message from the eNB further comprises information required for a PS handover, and after receiving the first Handover Request message from the eNB, the method comprises: sending, by the MME, a second Handover Request message to a serving general packet radio service (GPRS) support node (SGSN), wherein the second Handover Request message comprises the information required for the PS handover; and receiving, by the MME, a Handover Request ACK message returned by the SGSN, wherein the Handover Request ACK message comprises PS resource information prepared by the target BSS/RNS, and combining, by the MME, the Handover Request ACK message and the PS to CS Handover Response message so that the Handover Command message further comprises the PS resource information prepared by the target BSS/RNS.