This Global System for Mobile communications Technical Specification ( GTS) describes the subset of Base Station System Application Part (BSS AP) messages and procedures, defined in GSM 08.06 and GSM 08.08, which is used on the E-interface. A general description can be found in GSM 03.02 and GSM 03.09. For the initiation and execution of handover between MSCs a subset of BSSMAP procedures are used. For the subsequent control of resources al located to the Mobile Station (MS) BSSMAP procedures are used. DTAP is used for the transfer of connection management and mobility managemen t messages between the MS and the controlling MSC.