In
telecommunications
Telecommunication, often used in its plural form or abbreviated as telecom, is the transmission of information over a distance using electronic means, typically through cables, radio waves, or other communication technologies. These means of ...
, an electronic switching system (ESS) is a
telephone switch
A telephone exchange, telephone switch, or central office is a central component of a telecommunications system in the public switched telephone network (PSTN) or in large enterprises. It facilitates the establishment of communication circuits ...
that uses
solid-state electronics, such as
digital electronics
Digital electronics is a field of electronics involving the study of digital signals and the engineering of devices that use or produce them. It deals with the relationship between Binary number, binary inputs and outputs by passing electrical s ...
and
computer
A computer is a machine that can be Computer programming, programmed to automatically Execution (computing), carry out sequences of arithmetic or logical operations (''computation''). Modern digital electronic computers can perform generic set ...
ized
common control, to interconnect telephone circuits for the purpose of establishing telephone calls.
The generations of telephone switches before the advent of electronic switching in the 1950s used purely
electro-mechanical relay systems and analog voice paths. These early machines typically utilized the
step-by-step technique. The first generation of electronic switching systems in the 1960s were not entirely digital in nature, but used
reed relay-operated metallic paths or
crossbar switch
In electronics and telecommunications, a crossbar switch (cross-point switch, matrix switch) is a collection of switches arranged in a Matrix (mathematics), matrix configuration. A crossbar switch has multiple input and output lines that form a ...
es operated by
stored program control (SPC) systems.
First announced in 1955, the first customer trial installation of an all-electronic
central office commenced in
Morris, Illinois in November 1960 by
Bell Laboratories.
The first large-scale electronic switching system was the
Number One Electronic Switching System (1ESS) of the
Bell System, cut over in
Succasunna,
New Jersey
New Jersey is a U.S. state, state located in both the Mid-Atlantic States, Mid-Atlantic and Northeastern United States, Northeastern regions of the United States. Located at the geographic hub of the urban area, heavily urbanized Northeas ...
, in May 1965.
Just three years later, in September 1968, Britain's Post Office opened the world's first all-digital
pulse-code modulation (PCM) exchange named ''Empress'' (three decades after British scientist
Alec Reeves had invented the PCM encoding system without the digital components to take full advantage).
Other nations vying to reach the forefront of technical innovation would adopt
metal–oxide–semiconductor (MOS) and PCM technologies to make their own transitions from analog to
digital telephony throughout the 1970s.
Later electronic switching systems implemented the digital representation of the electrical audio signals on
subscriber loops by digitizing the analog signals and processing the resulting data for transmission between central offices.
Time-division multiplexing (TDM) technology permitted the simultaneous transmission of multiple telephone calls on a single wire connection between central offices or other electronic switches, resulting in dramatic capacity improvements of the
telephone network.
With the advances of digital electronics starting in the 1960s telephone switches employed
semiconductor device
A semiconductor device is an electronic component that relies on the electronic properties of a semiconductor material (primarily silicon, germanium, and gallium arsenide, as well as organic semiconductors) for its function. Its conductivit ...
components in increasing measure.
In the late 20th century most telephone exchanges without TDM processing were eliminated and the term ''electronic switching system'' became largely a historical distinction for the older SPC systems.
See also
*
List of telephone switches
*
Stored program control
*
5ESS Switching System
References
*
{{Telephone Switches
Telephone exchanges