The development of multimedia services is pushing networking technologies towards broadband solutions. A lot of research and development effort has been spent on finding a universal transport solution to carrying the different services to end-users. However, it looks that there will be no unifying transport solution to overcome the burden of networking diversity. This implies that the future services are delivered to users over heterogeneous networks. Therefore, interworking between the different networks and between the different signalling protocols becomes an essential part of the game. This paper introduces an interworking signalling solution for a switching equipment that integrates PDH time-slot and ATM cell switching. The switching platform is based on a multidiscipline switching fabric previously utilized in ATM switching applications.