Stored Program Controlled Network: Routing of Direct-Signaling Messagesin the CCIS Network

This paper describes the basic components and message routing in the common-channel interoffice signaling (ccis) network. Examples are used to show how direct signaling supports services which may be provided by offices connected to the new ccis network. Basic knowledge of the existing ccis network is assumed, but background information may be obtained from Ref. 1. Since its introduction in 1976, the ccis network has been providing addressing and routing of trunk-related telephone signaling messages for interconnection of switching offices. In 1980, a new capability, 1599 direct signaling, was added which significantly augments the network's capability to interconnect Stored Program Control (SPC) systems. The evolving network is called the SPC network, reflecting that offices interconnected by the signaling network have new stored program capabilities and are no longer connected only for trunk-related ccis signaling. Whereas telephone messages routed by band are confined to a preassigned end-to-end signaling path, direct-signaling messages are not banded but contain a full destination address. Direct-signaling messages are addressed by offices to gain access to a network feature. The signal transfer points (STPS) route direct-signaling messages to their destination address, regardless of where in the network the message originates, independent of any assigned signal paths. The typical direct-signaling relationship is not between two switching offices but is between an action point (ACP) and a dialed-number translation data base, called a network control point (NCP).