No. 1 ESS Call Processing

Abstract

A telephone call goes through six basic stages: (1) detection of a service request, (2) interpretation of the digits dialed, (3) alerting the called customer, (4) establishing a talking connection, (5) call disconnect, and (6) charging. The way in which programs, assisted by circuits and temporary memory, advance a call from one stage to another in no. 1 ESS is described in this article.