The Telephone Network


In order to get a telephone call to travel from one place to another, it must pass through the telephone network. This network consists of many different parts, operated by many different companies, but are inter-connected using common signaling methods. This section will discuss Central Offices, signaling between different telephone systems, different methods of transmission, and the use of tandems (transfer) in the network.

Telephone Network Systems Index

Telephone Central Office Switching Systems in North America - Past & Present
Details and history on vintage (electro-mechanical), modern (electronic & digital) and next-generation (packet-based softswitch) telephone switching systems used in the North American public switched telephone network. 

Telephone Network Signaling Technology
Details on the signaling methods used within the North American telephone network to allow central office and tandem systems to "talk" with each other.

Telephone Network Transmission Technology
Details on the physical means on how a telephone call is handled through the network between different systems.

Old (Historic) Number 4 Crossbar (#4XB) List
A list of locations where AT&T Long Lines (Bell System) used the Number 4 Crossbar (#4XB) Tandem system in the North American toll network from 1940s until the 1980s.

Other Telephone Network Systems websites (off-site)

Central Office Online
A website dedicated to central office systems, both past and present.






Copyright 2008 Telephone World
Page last modified December 20, 2008
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