Electronic switching system

In <a href="/facts/Telecommunications/vxoj1cxR">telecommunications</a>, an electronic switching system (ESS) is a <a href="/facts/Telephone_switch/PaRpGm8I">telephone switch</a> that uses <a href="/facts/Solid-state_electronics/US0Qbq28">solid-state electronics</a>, such as <a href="/facts/Digital_electronics/3kJcKbkw">digital electronics</a> and <a href="/facts/Computer/SQe1aK05">computer</a>ized <a href="/facts/Common_control/shEhVYDp">common control</a>, 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 <a href="/facts/Electro-mechanical/0D5gkXko">electro-mechanical</a> relay systems and analog voice paths. These early machines typically utilized the <a href="/facts/Stepping_switch/NWMDvf1w">step-by-step</a> technique. The first generation of electronic switching systems in the 1960s were not entirely digital in nature, but used <a href="/facts/Reed_relay/unwMsTps">reed relay</a>-operated metallic paths or <a href="/facts/Crossbar_switch/fSDXkMzf">crossbar switches</a> operated by <a href="/facts/Stored_program_control/FXtRRPlr">stored program control</a> (SPC) systems.
First announced in 1955, the first customer trial installation of an all-electronic <a href="/facts/Telephone_exchange/PaRpGm8I">central office</a> commenced in <a href="/facts/Morris%2c_Illinois/JMY4L5Qk">Morris, Illinois</a> in November 1960 by <a href="/facts/Bell_Laboratories/fKP5Gk0H">Bell Laboratories</a>. The first large-scale electronic switching system was the <a href="/facts/Number_One_Electronic_Switching_System/zLe0sHrF">Number One Electronic Switching System</a> (1ESS) of the <a href="/facts/Bell_System/GspEoeEF">Bell System</a>, cut over in <a href="/facts/Succasunna/r8VG8n7a">Succasunna</a>, <a href="/facts/New_Jersey/pI5k19S7">New Jersey</a>, in May 1965.
Just three years later, in September 1968, Britain's Post Office opened the world's first all-digital <a href="/facts/Pulse-code_modulation/5gdfjtH3">pulse-code modulation</a> (PCM) exchange named Empress (three decades after British scientist <a href="/facts/Alec_Reeves/mw1zsd1e">Alec Reeves</a> 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 <a href="/facts/Metal%25E2%2580%2593oxide%25E2%2580%2593semiconductor/eTDJT2Km">metal–oxide–semiconductor</a> (MOS) and PCM technologies to make their own transitions from analog to <a href="/facts/Digital_telephony/2GwTTepw">digital telephony</a> throughout the 1970s. Later electronic switching systems implemented the digital representation of the electrical audio signals on <a href="/facts/Subscriber_loop/rSRfLPaq">subscriber loops</a> by digitizing the analog signals and processing the resulting data for transmission between central offices. <a href="/facts/Time-division_multiplexing/tv7bMh1v">Time-division multiplexing</a> (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 <a href="/facts/Public_switched_telephone_network/eVrCTDU7">telephone network</a>.
With the advances of digital electronics starting in the 1960s telephone switches employed <a href="/facts/Semiconductor_device/6W3ryr50">semiconductor device</a> 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.

Electronic switching system open-in-new

Electronic switching system