Editing Electronic switching system

In [[telecommunications]], an '''electronic switching system''' ('''ESS''') is a [[telephone switch]] that uses [[solid-state electronics]], such as [[digital electronics]] and [[computer]]<nowiki/>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 [[Stepping switch|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]]es operated by [[stored program control]] (SPC) systems.

First announced in 1955, the first customer trial installation of an all-electronic [[Telephone exchange|central office]] commenced in [[Morris, Illinois]] in November 1960 by [[Bell Laboratories]].<ref name="ess">{{cite book  | date=April 1960 | title=The Electronic Switching System | last=Duhnkrack | first=George | publisher=Bell Telephone Laboratories, Incorporated | url=https://archive.org/details/TheElectronicSwitchingSystem | ol=24657942M | page=[https://archive.org/details/TheElectronicSwitchingSystem/page/n8 1]}}</ref> 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]], 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).<ref>{{cite web | url=https://www.sciencemuseum.org.uk/objects-and-stories/goodbye-hello-girls-automating-telephone-exchange | title=Goodbye to the hello girls: Automating the telephone exchange &#124; Science Museum }}</ref> 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.<ref name="Allstot">{{cite book |last1=Allstot |first1=David J. |chapter=Switched Capacitor Filters |editor-last1=Maloberti |editor-first1=Franco |editor-last2=Davies |editor-first2=Anthony C. |title=A Short History of Circuits and Systems: From Green, Mobile, Pervasive Networking to Big Data Computing |date=2016 |publisher=[[IEEE Circuits and Systems Society]] |isbn=9788793609860 |pages=105–110 |url=https://ieee-cas.org/sites/default/files/a_short_history_of_circuits_and_systems-_ebook-_web.pdf |archive-url=https://ghostarchive.org/archive/20221009/https://ieee-cas.org/sites/default/files/a_short_history_of_circuits_and_systems-_ebook-_web.pdf |archive-date=2022-10-09 |url-status=live}}</ref><ref name="Gibson26">{{cite book |last1=Floyd |first1=Michael D. |last2=Hillman |first2=Garth D. |chapter=Pulse-Code Modulation Codec-Filters |title=The Communications Handbook |edition=2nd |date=8 October 2018 |orig-year=1st pub. 2000 |pages=26-1, 26-2, 26-3 |publisher=[[CRC Press]] |isbn=9781420041163 |chapter-url=https://books.google.com/books?id=Tokk5bZxB0MC&pg=SA26-PA1}}</ref> Later electronic switching systems implemented the digital representation of the electrical audio signals on [[subscriber loop]]s 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 [[Public switched telephone network|telephone network]].

With the advances of digital electronics starting in the 1960s telephone switches employed [[semiconductor device]] 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==
{{Reflist}}
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*{{FS1037C MS188}}
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{{Telephone Switches}}

[[Category:Telephone exchanges]]