An electronic-private-branch-exchange telephone switching system

A new electronic private-branch-exchange (PBX), known as the No. 101 Electronic Switching System (ESS), has been developed to provide telephone switching service for business customers. A field trial system has recently been installed. This system is compatible with existing station and central office equipment and provides presently available telephone services. In addition, it takes advantage of the inherent speed of electronic devices and has improved flexibility for providing a continually increasing and changing set of new service features. The separation of the switching and control functions permits relatively small remote PBX´s to share the common control economically. This paper describes the over-all system and serves to coordinate other papers^1–3 which describe in more detail the system design and operation.