ISDN Conformance Testing at AT&T

AT&T Bell Laboratories has been involved in testing equipment for conformance with network and product interface specifications for more than five years. It has been an interesting and exciting period over which we have watched interfaces progress from rather simple, physical layer interfaces to increasingly complex protocal-oriented interfaces. The first protocal we tested was X.25 which provides the interface to AT&T's Account(R) Packet Service. X.25 conformance testing has been conducted for over four years. The ISDN Basic Rate Interface protocal as specified for the 5ESS sup TM switch followed shortly thereafter. Testing of the ISDN Primary Rate Interface protocal, the ISDN interface to our long distance network service has been in process for about one year. We have gained significant experience in protocol testing with almost 100 units tested for conformance with these interfaces.