The Cable and Telecommunications Professionals' Reference, 3rd Edition

Part Two

Circuit-switched Networks and Digital Switching Systems

Circuit-switched telephone networks have provided voice communications for more than a century. Over much of the period, their development has been relatively slow, with major changes taking place only rarely. For example, in the 1950s subscriber trunk dialing was introduced, in the 1970s mobile phone networks emerged, and in the early 1980s new digital and switching transmission caused a transition from analogue to digital technology, which was later accelerated by the appearance of optical fiber transmission. Since then, new calling features enabled by digital operation and voice processing have progressively improved the service over the years and, more recently, Internet telephony ...