DS TS 129 118 V13.7.0:2018

Universal Mobile Telecommunications System (UMTS); LTE; Mobility Management Entity (MME) - Visitor Location Register (VLR) SGs interface specification (3GPP TS 29.118 version 13.7.0 Release 13)

Scope

CS Fallback in the Evolved Packet System (EPS) enables the provisioning of CS-domain services (e.g. voice call,
Location Services (LCS) or supplementary services) by reuse of CS infrastructure when the UE is served by E-UTRAN.
Additionally, SMS delivery via the CS core network is realized without CS fallback.
The present document specifies the procedures and the SGs Application Part (SGsAP) messages used on the SGs
interface between the Mobility Management Entity (MME) in the EPS and the Visitor Location Register (VLR), to
allow location management coordination and to relay certain messages related to GSM circuit switched services over
the EPS system.
The present document also specifies the use of Stream Control Transmission Protocol (SCTP) for the transport of
SGsAP messages.
The present document is applicable to the MME in the EPS and to the VLR. The functional split between the MME and
the VLR is defined in 3GPP TS 23.272 [7].