To permit negotiation of connections over the Asynchronous Transfer Mode, a signaling function is required. This signaling function, in turn, makes use of an assured data delivery service. This service is provided by the Service Specific Connection Oriented Protocol (SSCOP), which resides in the ATM Adaptation Layer (AAL).  A specification of the SSCOP has been developed in Estelle. In addition, testing modules representing the action of the user, the action of the management entity and the fault module of the underlying unassured data delivery service have been developed.