View source for System Y

{{Short description|Digital switching system}}
'''System Y''' is the terminology used by [[BT Group|BT]], the main operator of the telephone network in the [[United Kingdom]], to refer to the [[Ericsson]] [[AXE telephone exchange|AXE]] digital switching system.

In the mid-1980s, British Telecom chose the well established [[AXE10]] digital switch to provide competition for [[System X (telephony)|System X]] developed by a consortium of [[Plessey]], [[General Electric Company]] (GEC) (companies later combined as GPT), [[Standard Telephones and Cables|STC]] and BT's state owned predecessor, the [[General Post Office|GPO]]. The newly privatised BT brought in Ericsson as a competitive alternative supplier ending Plessey/GEC's monopoly on the provision of switching systems. 

Initially, the AXE systems installed in the UK were partially locally manufactured in partnership with [[Thorn EMI]] and later directly by Ericsson. While System X exchanges were more widespread in BT's network, AXE10 (and subsequent versions) remain common in the classic BT [[public switched telephone network|PSTN]] until their eventual replacement when the network is closed, which at the time of the writing is expected to be in 2027 <ref>{{Cite web|url=https://business.bt.com/insights/uk-pstn-switch-off/|title=The UK’s PSTN network will switch off in 2027}}</ref>

AXE10 covers two main types of [[digital telephony]] switching equipment: the remote subscriber switch (RSS) and the AXE10 local switch. RSS acts as a [[remote concentrator]] and deals with the conversion of analogue telephony signals used in the [[access network]], which is the copper pairs between exchange buildings and customer premises, also called [[local loop]], and the multiplexing of customer lines over cabling to the AXE10 local switching unit. The AXE10 local switch uses a processor-controlled switch to route calls and data depending on the destination of the telephony transmission.

BT's AXE10 network, which has been in service since 1986,<ref>[http://www.connected-earth.com/Galleries/Frombuttonstobytes/Digitaltelephony/Digitalswitching/index.htm "Digital Switching"] {{Webarchive|url=https://web.archive.org/web/20080725044548/http://www.connected-earth.com/Galleries/Frombuttonstobytes/Digitaltelephony/Digitalswitching/index.htm |date=2008-07-25 }}, ''Connected Earth'', accessed 2009-05-17</ref> is maintained in house by its own engineers although [[Ericsson]] still provide high-level support, software upgrades and repairs at component level.

AXE/System Y, System X and other [[Time-division multiplexing|TDM]] technologies are already being be phased out as BT, in common with many networks around the world, implements its next generation access network, which will ultimately be based predominantly on fibre to premises (FTTP), with voice services provided using [[Voice over IP|VoIP]] technology. <ref>{{Cite web|url=https://www.ispreview.co.uk/index.php/2019/05/openreach-aim-for-15-million-uk-fttp-broadband-premises-by-2025.html|title = Openreach Aim for 15 Million UK FTTP Broadband Premises by 2025|date = 9 May 2019}}</ref>

==References==
{{reflist}}

{{BT Group}}

[[Category:History of telecommunications in the United Kingdom]]
[[Category:Telephone exchange equipment]]
[[Category:BT Group]]

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