The present document provides a set of interoperability use cases to be tested in order to validate an interconnection between IMS and EPC subsystems. For each use case there are conformance criteria and Test Descriptions (TD) detailed. The target of the present document is to provide the boiler-plate for verifing interoperability between the IMS and EPC subsystems based on the exemplary scenarios network attachment@ IMS registration and IMS session management. Verifying basic protocol interoperability or NNI interoperability between two peer EPC systems is out of scope of the present document.