Evolved Packet System (EPS); 3GPP Sv interface (MME to MSC, and SGSN to MSC) for SRVCC
The present document describes the Sv interface between the Mobility Management Entity (MME) or Serving GPRS Support Node (SGSN) and 3GPP MSC server enhanced for SRVCC. Sv interface is used to support Inter-RAT handover from IMS based voice service over EPS to CS domain over 3GPP UTRAN/GERAN access or from UTRAN (HSPA) to 3GPP UTRAN/GERAN access and to support Inter-RAT handover from IMS based voice and video service over EPS to CS domain over 3GPP UTRAN access. Sv interface is also used to support Inter-RAT handover from voice service in CS domain over 3GPP UTRAN/GERAN access to IMS based service over LTE or UTRAN (HSPA).
If there is no specific indication, the term "MSC server" denotes 3GPP MSC server enhanced for SRVCC or 3GPP MSC server enhanced for vSRVCC as defined in 3GPP TS 23.216 [2].