Information on other modern electronic and digital telephone switching of note.
Siemens Digital Switching Systems
Siemens of Germany is a well-known manufacturer of telephone equipment. Their main switch for the public switched telephone network is the the EWSD (Electronic World Switch Digital – a medium to high capacity switch) for both the North American and world markets. Siemens started the manufacture of the EWSD in 1976. It is now a division of Nokia Networks.
Siemens EWSD switch (photo: Telcordia)
The Stromberg-Siemens divsion manufactured the DCO (Digital Central Office) as a medium capacity central office switch (see description below).
Stromberg-Carlson Electronic & Digital Switches
Stromberg-Carlson was known for their more famous XY line of Step by Step switches, but in the 1970s developed their own electronically controlled analog switch.
This switch was known as the Electronic Switching Center (ESC) that was developed in the early 1970s. The ESC was a “crossreed” switch that used reed relays instead of mechanical crossbars. The known variants of the ESC were the ESC-1 and ESC-3.
In 1977, Stromberg-Carlson developed their own digital central office, known quite affectionately as the Digital Central Office (DCO). The DCO is designed for a small to medium capacity switch.
In 1982, General Dynamics (then owner) sold the telephone set manufacturing arm to Comdial of Charlottesville, VA – while selling the telephone switch manufacturing arm to Siemens of Germany.
Siemens manufactured the DCO switch until recently along with their own line of central office switches (see Siemens section above).
Other digital switches that are also used in the North American Market:
Redcom Laboratories: MDX-384
Modern Telephone Switching Systems Index
Overview & Background of Modern (Electronic & Digital Switching) Systems
Automatic Electric Modern Switching Systems
Northern Telecom (Nortel) Modern Switching Systems
TRW-Vidar Switching Systems
Other Modern Switching Systems of Note
Western Electric/Lucent Technologies