Theoretically, conformance yields interworking and interoperability. However, experience has shown problems even when systems are conforming to the same standard. By having a glance at its methodology, conformance testing addresses the tested system as an isolated entity. Prior to real procurement, on the other hand, network operators apply a set of modifications that make a system applicable to their environment. As a result of these modifications, conformity, possibly, will have new significance and definition. Any other system, moreover, could be a subject of similar action. This puts the conformity relation on edge, and makes implication of interoperability a hope rather than a culmination. This paper proposes an approach for generating interoperability test suite from the relevant conformance test suite.