Editing System X (telephony) (section)

===Development===
System X was developed by [[Post Office Telecommunications]] (later to become [[British Telecom]]), [[General Electric Company|GEC]], [[Plessey]], and [[Standard Telephones and Cables]] (STC), and was first shown in public in 1979 at the Telecom 79 exhibition in Geneva, Switzerland.<ref>{{Cite web|title=Exhibits: System X|url=https://www.communicationsmuseum.org.uk/systemx/|access-date=2021-05-27|website=The Communications Museum Trust}}</ref> STC withdrew from the project in 1982. In 1988, the telecommunications divisions of GEC and Plessey merged to form [[GEC Plessey Telecommunications|GPT]], with Plessey subsequently being bought out by GEC and [[Siemens]]. In the late 1990s, GEC acquired Siemens' 40% stake in GPT. GEC renamed itself [[Marconi Electronic Systems|Marconi]] in 1999.

When Marconi was sold to [[Ericsson]] in January 2006, [[Telent|Telent plc]] retained System X and continues to support and develop it as part of its UK services business.