Abstract

Research and development underway 30 years ago brought about today’s world of stored program controlled digital switching. The confluence of three key elements was the trigger for this new era in switching--the transistor, the basic concepts of stored program controlled computing, and the techniques of digital communication in the form of PCM. Today, roughly one quarter of the world’s 400 million telephone lines are served by central offices deploying most of these technologies. Though stored program gave these switches considerable new flexibility for customer features and allowed great strides in automation and simplification of maintenance and operations, the new technology was primarily deployed as a one-for-one cost reduction element for its electromechanical predecessors in the existing network--effectively a replacement vehicle between existing mainframes.

© 1987 Optical Society of America