The present document describes the Abstract Test Suite (ATS) to test interoperability for interconnection between IMS and EPC subsystems@ based on TS 123 401 [4]. The ATS has been specified on the basis of the Test Descriptions for IMS/EPC interoperability testing presented in TS 103 029 [i.1]. It defines a TTCN-3 framework as well as codec and adapter requirements for analysing interoperability test execution traces generated from the manual or automatic execution of IMS interoperability tests. The scope of this ATS is not to cover all requirements specified in TS 124 229 [1]. It only assesses requirements that are observable at the NMI between EPC and IMS core network implementations specified in TS 103 029 [i.1].