Datakit
Datakit is a virtual circuit switch which was developed by Sandy Fraser at Bell Labs for both local-area and wide-area networks, and in widespread deployment by the Regional Bell Operating Companies (RBOCs).
Datakit uses a cell relay protocol similar to Asynchronous Transfer Mode. Datakit is a connection-oriented switch; hence all packets for a particular call travel through the network over the same virtual circuit. Datakit networks are still in widespread use by the major telephone companies in the United States.