Conformance testing is a crucial activity which aims at stimulating the communication system under test (SUT) to detect errors and unexpected behaviors with regards to the standards. However, when considering distributed systems, the joint and linked stimulation of distributed entities is not easy. The correlation of verdicts obtained from these entities is most of the time impossible in a real environment because of inherent constraints and specific assumptions. In this paper, we present a novel distributed testing architecture based on a formal definition of test cases dependencies to test the conformance of distributed systems in a black box context. Finally, we successfully apply our approach to a real IMS/SIP test bed and perform the tests through one SIP use case