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1. (WO2018161804) METHOD AND SYSTEM FOR SWITCHING FROM IMS CALL TO CIRCUIT-SWITCHED CALL

Pub. No.:    WO/2018/161804    International Application No.:    PCT/CN2018/077037
Publication Date: Fri Sep 14 01:59:59 CEST 2018 International Filing Date: Sat Feb 24 00:59:59 CET 2018
IPC: H04L 29/06
Applicants: ZTE CORPORATION
中兴通讯股份有限公司
Inventors: LIU, Jingxiang
刘竞翔
Title: METHOD AND SYSTEM FOR SWITCHING FROM IMS CALL TO CIRCUIT-SWITCHED CALL
Abstract:
The invention discloses a method and system for switching from an IMS call to a circuit-switched call. The switching method comprises: when a user terminal in an ongoing IMS call moves from a packet-switched domain network to a location where there is only a circuit-switched domain network available, a vMSCS receiving a switching preparation request transmitted by an eMSCS and comprising a STN-SR used to indicate that a destination address is an ATCF; and the vMSCS utilizing the STN-SR in the switching preparation request to establish a multimedia link to the ATCF, so that when the user terminal switches to and accesses the circuit-switched domain network via the vMSCS, the client terminal can continue, via the multimedia link, the IMS call with another user terminal in the IMS call.