The Cable and Telecommunications Professionals' Reference, 3rd Edition

Part 1

For most of the past century, the main purpose of telecommunications networks has been to enable voice communications between people at a distance. To a lesser extent it has included communications between people and voice recording or playback devices, such as automatic voice response systems. In more recent decades, there has also been a steady growth in the use of telecommunications networks to provide data connections for applications such as remote sensing, transfering data between data centers, or carrying TV signals in digital format. However, more recently, the emphasis has shifted very much toward the provision of connections between information systems or between people and information systems capable of carrying voice, video, ...