The scope of this Technical Specification is to provide a detailed specification for interworking between the A interface protocol and the Mobile Application Part for handling of supplementary services. The MAP interfaces of interest are the B-@ C-@ D- and E-interfaces. The A-@ C-@ D- and E-interfaces are physical interfaces while the B-interface is an internal interface defined for modelling purposes. Information relating to the modelling interface is not normative in this specification. Supplementary service signalling may be passed by the MSC/VLR between the A- and E-interfaces after inter-MSC handover. This procedure is transparent as far as supplementary services are concerned therefore interworking concerning this process is not described in this specification. Clause 2 describes general procedures for interworking between the A- and D- physical interfaces. Clause 3 describes the general procedures for the SS version negotiation. Clause 4 describes the mapping of layer 3 radio path messages with Transaction Capabilities (TC) transaction sublayer messages for interworking between the A- and D- physical interfaces. Clause 5 describes specific interworking procedures for all interfaces relating to call related SS activity. Clause 6 describes specific interworking procedures for all interfaces relating to call independent SS activity. Clause 6 also covers the interworking between the MAP User (see GSM 09.02) and the SS handling functions of the network entities (see GSM 04.10 and GSM 04.80). Reference is made to the following Technical Specifications: - GSM 02.04 and GSM 02.8x and GSM 02.9x-series@ for definition of supplementary services; - GSM 03.11@ GSM 03.8x and GSM 03.9x-series@ for technical realisation of supplementary services; - GSM 04.10@ GSM 04.80@ GSM 04.8x and GSM 04.9x-series@ for radio path signalling procedures for supplementary services; - GSM 09.02 (MAP).