Transaction Network, Telephones, and Terminals: Transaction Network Operational Programs

The stored program for the Transaction Network (TN) directs the operation of equipment that provides switched communications of short data messages between terminals and Customer Service Centers and between two different Customer Service Centers. The system is designed to meet operational requirements differing from those imposed on other stored program switching systems, such as the No. 1 Electronic Switching System (ESS).1 Unlike such line-switched systems, a message-switched system provides no intrinsic end-to-end verification of the communication path or delivery of the message. The originating user relys on the system to properly deliver accepted messages to the appropriate destinations. This places stringent requirements on the message switching system to provide message protection, assurance of delivery, and privacy. The TN stored program is described in three parts: the call processing programs which support the various service features and protocols, the maintenance programs which maintain an operational system in the presence of troubles and diagnose the faulty units, and the administrative programs which allow the telephone company to input office parameters and customer information into memory and to obtain traffic and maintenance measurements reports and billing information. This paper provides an overview of the various programs. Companion papers cover the hardware structure and service capabilities. 3371