This TS specifies the stage 3 of the Evolved Packet System S102
interface between the MME and the 1x
CS IWS to relay the 1xCS signalling messages documented in TS 23.216
1x CS signalling messages are those messages that are defined for A21 interface as described in 3GPP2 A.S0008-C and 3GPP2 A.S0009-C.
interface messages shall be based on A21 messages.
interface is used to support UEs that do not transmit and receive on both the LTE and 1x radio interfaces
protocol aspects for SRVCC from E-UTRAN access to 3GPP2 1xCS is covered in this
specification. Handling of non-voice component and protocol aspects for SRVCC from 3GPP2 1xCS to E-UTRAN
direction is not specified in this release.