Switched digital capability: An overview

SDC (Switched Digital Capability) allows end-to-end circuit-switched 56 kb/s data over much of the existing Bell System Network. Since SDC is based largely on the stored program-controlled space and time-division switches, 2-wire local loops, and T-carrier facilities that are already deployed in the network, it can be realized with minimum modification to the existing network. SDC is expected to play a major role in the evolution of the present network to the ISDN (Integrated Services Digital Network) of the future.