Common Channel Interoffice Signaling: Field Implementation

Domestic CCIS will extend eventually to most SPC-type switching offices in the DDD network. The implementation plan 1 concentrates first on the toll portion of the network in order to realize the benefits of CCIS as soon as possible. Quasi-associated signaling is being used to form the initial domestic CCIS network. 2 This is a simple dual-level signaling network with ten regions corresponding geographically to the ten regions of the DDD message network. Each region has a Signal Transfer Point (STP), duplicated for reliability, which has signaling links to every other STP and to every CCIS-equipped Switching Office (SO) in its region. Since the basic topological element of this signaling network is a " q u a d " consisting of the two (mate) STPs in one region fully interconnected with the STP pair of another signaling region, and since construction of a full quad of laboratory STP entities would be impractical, the first two pairs of field STPs were scheduled to serve also as a test vehicle for system design verification. This initial quad consists of STPs at Indianapolis and Omaha for the Norway region and at Dallas and Oklahoma City for the Dallas region. As noted in Ref. 2, these STPs were derived from existing toll crossbar Electronic Translator System (ETS) 449