Telephone Switching Systems

This section discusses telephone switching systems, where phone calls are “switched” meaning they cross through a switching matrix to route calls from an origination point to a destination point.

Local “central offices” are where the end users are located. This is the most common switching system in the telephone network.

Long Distance “tandem” switches are where long-haul long distance calls are switched to connect local central office switches throughout the world.

North American (US/Canada) Vintage (electro-mechanical), Modern (analog and digital electronic) as well as cutting-edge packet-based switching systems are discussed here.


Step by Step (Strowger) Switching Systems
Details on the Step by Step (aka Strowger) switching system and its variants.

Western Electric Crossbar Switching Systems
Details on the Western Electric Crossbar switching system and its variants.


Western Electric/Lucent Technologies
Details on Western Electric (later Lucent Technologies) modern switching systems

Northern Telecom/Nortel
Details on Northern Telecom (now Nortel) electronic & digital switching systems.

Other Companies (Siemens, Stromberg-Carlson, ITT)
Details on other modern switching systems of note that are not mentioned above.

The Next Generation

Packet & Voice over IP
An overview on “softswitches”, the next generation telephone switching system that use Internet routing technologies to switch and route telephone calls.