This book is a thorough study of electronic switching, covering all aspects of the problem. It was written by a group of experienced switching engineers working for France's National Telecommunications Research Center (CNET). After a substantial review of general telephony, the authors discuss connection functions and their realization through either space division or time division, signalling principles on subscriber lines and trunk lines, traffic, network planning and operation and maintenance. Equipment and software are described from a didactic and functional approach. Theoretical aspects are illustrated using examples borrowed from the most modern electronic switching systems.