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<title>System Y</title>

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<span id="openzim-page-title" class="mw-page-title-main"><span class="mw-page-title-main">System Y</span></span>

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<p><b>System Y</b> is the terminology used by <a href="BT_Group" title="BT Group">BT</a>, the main operator of the telephone network in the <a href="United_Kingdom" title="United Kingdom">United Kingdom</a>, to refer to the <a href="Ericsson" title="Ericsson">Ericsson</a> <a href="AXE_telephone_exchange" title="AXE telephone exchange">AXE</a> digital switching system.

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

</p><p>Initially, the AXE systems installed in the UK were partially locally manufactured in partnership with <a href="Thorn_EMI" title="Thorn EMI">Thorn EMI</a> 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 <a href="Public_switched_telephone_network" title="Public switched telephone network">PSTN</a> until their eventual replacement when the network is closed, which at the time of the writing is expected to be in 2027 <sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup>

</p><p>AXE10 covers two main types of <a href="Digital_telephony" class="mw-redirect" title="Digital telephony">digital telephony</a> switching equipment: the remote subscriber switch (RSS) and the AXE10 local switch. RSS acts as a <a href="Remote_concentrator" title="Remote concentrator">remote concentrator</a> and deals with the conversion of analogue telephony signals used in the <a href="Access_network" title="Access network">access network</a>, which is the copper pairs between exchange buildings and customer premises, also called <a href="Local_loop" title="Local loop">local loop</a>, 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.

</p><p>BT's AXE10 network, which has been in service since 1986,<sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> is maintained in house by its own engineers although <a href="Ericsson" title="Ericsson">Ericsson</a> still provide high-level support, software upgrades and repairs at component level.

</p><p>AXE/System Y, System X and other <a href="Time-division_multiplexing" title="Time-division multiplexing">TDM</a> 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 <a href="Voice_over_IP" title="Voice over IP">VoIP</a> technology. <sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup>

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<div class="mw-heading mw-heading2"><h2 id="References">References</h2></div>

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</style><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://business.bt.com/insights/uk-pstn-switch-off/">"The UK's PSTN network will switch off in 2027"</a>.</cite></span>

</li>

<li id="cite_note-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-2">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="http://www.connected-earth.com/Galleries/Frombuttonstobytes/Digitaltelephony/Digitalswitching/index.htm">"Digital Switching"</a> <a rel="nofollow" class="external text" href="https://web.archive.org/web/20080725044548/http://www.connected-earth.com/Galleries/Frombuttonstobytes/Digitaltelephony/Digitalswitching/index.htm">Archived</a> 2008-07-25 at the <a href="Wayback_Machine" title="Wayback Machine">Wayback Machine</a>, <i>Connected Earth</i>, accessed 2009-05-17</span>

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<li id="cite_note-3"><span class="mw-cite-backlink"><b><a href="#cite_ref-3">^</a></b></span> <span class="reference-text"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.ispreview.co.uk/index.php/2019/05/openreach-aim-for-15-million-uk-fttp-broadband-premises-by-2025.html">"Openreach Aim for 15 Million UK FTTP Broadband Premises by 2025"</a>. 9 May 2019.</cite></span>

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</style><div id="BT_Group391" style="font-size:114%;margin:0 4em"><a href="BT_Group" title="BT Group">BT Group</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%">Divisions<br>and<br>subsidiaries</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:3em;text-align:left; background-color:#eee">Current</th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em">

<ul><li><a href="BT_Consumer" class="mw-redirect" title="BT Consumer">BT Consumer</a></li>

<li><a href="BT_Business_and_Public_Sector" title="BT Business and Public Sector">BT Business and Public Sector</a></li>

<li><a href="BT_Global_Services" title="BT Global Services">BT Global Services</a></li>

<li><a href="BT_Wholesale_and_Ventures" title="BT Wholesale and Ventures">BT Wholesale and Ventures</a></li>

<li><a href="BT_Research" title="BT Research">BT Research</a></li>

<li><a href="Openreach" title="Openreach">Openreach</a></li>

<li><a href="Plusnet" title="Plusnet">Plusnet</a></li>

<li><a href="BT_Ireland" title="BT Ireland">BT Ireland</a></li>

<li><a href="BT_Italia" title="BT Italia">BT Italia</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:3em;text-align:left; background-color:#eee">Former</th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Global_Marine_Systems" title="Global Marine Systems">BT Marine</a></li>

<li><a href="Madasafish" class="mw-redirect" title="Madasafish">Madasafish</a>

<ul><li><small>merged into <a href="Plusnet" title="Plusnet">Plusnet</a></small></li></ul></li>

<li><a href="Manx_Telecom" title="Manx Telecom">Manx Telecom</a></li>

<li><a href="O2_(Ireland)" title="O2 (Ireland)">O2 (Ireland)</a></li>

<li><a href="Telef%C3%B3nica_Germany" title="Telefónica Germany">O2 (Germany)</a></li>

<li><a href="Ribbit_(telecommunications_company)" title="Ribbit (telecommunications company)">Ribbit</a></li>

<li><a href="Concert_Communications_Services" title="Concert Communications Services">Concert Communications Services</a></li>

<li><a href="Telecomsoft" title="Telecomsoft">Telecomsoft</a></li>

<li><a href="Tymnet" title="Tymnet">Tymnet</a></li>

<li><a href="International_Network_Services_Inc." title="International Network Services Inc.">International Network Services</a></li>

<li><a href="Dialcom" title="Dialcom">Dialcom</a></li>

<li><a href="Telfort" title="Telfort">Telfort</a></li>

<li><a href="LineOne" title="LineOne">LineOne</a></li>

<li><a href="Swindon_Cable" title="Swindon Cable">Swindon Cable</a></li>

<li><a href="6GMOBILE" class="mw-redirect" title="6GMOBILE">6GMOBILE</a></li>

</div></td></tr></tbody></table><div></div></td><td class="noviewer navbox-image" rowspan="6" style="width:1px;padding:0 0 0 2px"><div><span typeof="mw:File"></span></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Products<br>and<br>services</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:3em;text-align:left; background-color:#eee">Current</th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em">

<ul><li><a href="BT_Broadband" title="BT Broadband">BT Broadband</a></li>

<li><a href="EE_(telecommunications)" title="EE (telecommunications)">EE Broadband</a></li>

<li><a href="EE_(telecommunications)" title="EE (telecommunications)">EE Mobile</a></li>

<li><a href="BT_Smart_Hub" title="BT Smart Hub">BT Smart Hub</a></li>

<li><a href="TNT_Sports_(United_Kingdom)" title="TNT Sports (United Kingdom)">TNT Sports</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:3em;text-align:left; background-color:#eee">Defunct</th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em">

<ul><li><a href="BT_Fusion" title="BT Fusion">BT Fusion</a></li>

<li><a href="BT_Highway" title="BT Highway">BT Highway</a></li>

<li><a href="BT_Mobile" title="BT Mobile">BT Mobile</a></li>

<li><a href="BT_Superfast_Fibre" title="BT Superfast Fibre">BT Superfast Fibre</a></li>

<li><a href="BT_Versatility" title="BT Versatility">BT Versatility</a></li>

<li><a href="BT_Voyager" title="BT Voyager">BT Voyager</a></li>

<li><a href="BT_MyDonate" title="BT MyDonate">BT MyDonate</a></li>

<li><a href="BT_MyPlace" title="BT MyPlace">BT MyPlace</a></li>

<li><a href="Telecom_Gold" title="Telecom Gold">Telecom Gold</a></li>

<li><a href="Micronet_800" title="Micronet 800">Micronet 800</a></li>

<li><a href="Merlin_M4000" title="Merlin M4000">Merlin M4000</a></li></ul>

</div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Buildings<br>and<br>facilities</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:3em;text-align:left; background-color:#eee">Current</th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Adastral_Park" title="Adastral Park">Adastral Park</a></li>

<li><a href="Baynard_House%2C_London" title="Baynard House, London">Baynard House</a></li>

<li><a href="BT_Centre" class="mw-redirect" title="BT Centre">BT Centre</a></li>

<li><a href="BT_Tower" title="BT Tower">BT Tower (London)</a></li>

<li><a href="BT_Tower_(Birmingham)" class="mw-redirect" title="BT Tower (Birmingham)">BT Tower (Birmingham)</a></li>

<li><a href="BT_Tower_(Swansea)" title="BT Tower (Swansea)">BT Tower (Swansea)</a></li>

<li><a href="BT_Riverside_Tower" title="BT Riverside Tower">BT Riverside Tower</a></li>

<li><a href="Stadium_House%2C_Cardiff" title="Stadium House, Cardiff">Stadium House</a></li>

<li><a href="Charwelton_BT_Tower" title="Charwelton BT Tower">Charwelton BT Tower</a></li>

<li><a href="Faraday_Building" title="Faraday Building">Faraday Building</a></li>

<li><a href="Goonhilly_Satellite_Earth_Station" title="Goonhilly Satellite Earth Station">Goonhilly Cornwall</a></li>

<li><a href="Guardian_telephone_exchange" title="Guardian telephone exchange">Guardian Exchange Manchester</a></li>

<li><a href="Madley_Communications_Centre" title="Madley Communications Centre">Madley Communications Centre</a></li>

<li><a href="National_Network_Management_Centre" title="National Network Management Centre">National Network Management Centre</a></li>

<li><a href="Peterborough_transmitting_station" title="Peterborough transmitting station">Peterborough transmitting station</a></li>

<li><a href="Zouches_Farm_transmitting_station" title="Zouches Farm transmitting station">Zouches Farm transmitting station</a></li>

<li><a href="Heaton_Park_BT_Tower" title="Heaton Park BT Tower">Heaton Park BT Tower</a></li>

<li><a href="Purdown_BT_Tower" title="Purdown BT Tower">Purdown BT Tower</a></li>

<li><a href="Pye_Green_BT_Tower" title="Pye Green BT Tower">Pye Green BT Tower</a></li>

<li><a href="Stokenchurch_BT_Tower" title="Stokenchurch BT Tower">Stokenchurch BT Tower</a></li>

<li><a href="Sutton_Common_BT_Tower" title="Sutton Common BT Tower">Sutton Common BT Tower</a></li>

<li><a href="Tinshill_BT_Tower" title="Tinshill BT Tower">Tinshill BT Tower</a></li>

<li><a href="Tolsford_Hill_BT_Tower" title="Tolsford Hill BT Tower">Tolsford Hill BT Tower</a></li>

<li><a href="Wotton-under-Edge_BT_Tower" title="Wotton-under-Edge BT Tower">Wotton-under-Edge BT Tower</a></li>

<li><a href="Red_telephone_box" title="Red telephone box">Red telephone box</a></li>

<li><a href="KX_telephone_boxes" title="KX telephone boxes">KX telephone boxes</a></li>

<li><a href="LinkUK" title="LinkUK">LinkUK</a></li></ul>

<ul><li><a href="Anchor_telephone_exchange" title="Anchor telephone exchange">Anchor telephone exchange</a></li>

<li><a href="Bletchley_Park" title="Bletchley Park">Bletchley Park</a></li>

<li><a href="C.S._Sovereign" title="C.S. Sovereign"><i>C.S. Sovereign</i></a></li>

<li><a href="De_Vere_Horwood_Estate" class="mw-redirect" title="De Vere Horwood Estate">Horwood House</a></li>

<li><a href="Kingsway_telephone_exchange" title="Kingsway telephone exchange">Kingsway telephone exchange</a></li>

<li><a href="Leafield_Technical_Centre" title="Leafield Technical Centre">Leafield Technical Centre</a></li>

<li><a href="Mondial_House" title="Mondial House">Mondial House</a></li>

<li><a href="Stag_Lane_Aerodrome" title="Stag Lane Aerodrome">Stag Lane Aerodrome</a></li>

<li><a href="Graham_Hills_Building" title="Graham Hills Building">Marland House</a></li>

<li><a href="Vita_Student_Sheffield" title="Vita Student Sheffield">Sheffield Telephone House</a></li>

<li><a href="Post_Office_Research_Station" title="Post Office Research Station">Post Office Research Station</a></li>

<li><a href="Portishead_Radio" title="Portishead Radio">Portishead Radio</a></li>

<li><a href="Criggion_Radio_Station" title="Criggion Radio Station">Criggion Radio Station</a></li>

<li><a href="Rugby_Radio_Station" title="Rugby Radio Station">Rugby Radio Station</a></li>

<li><a href="British_Telecom_microwave_network" title="British Telecom microwave network">Microwave network</a></li>

<li><a href="CANTAT-2" title="CANTAT-2">CANTAT-2</a></li>

<li><a href="UK-Belgium_5" title="UK-Belgium 5">UK-Belgium 5</a></li></ul>

</div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Programmes<br>and<br>standards</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:3em;text-align:left;background-color:#eee">Current</th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em">

<li><a href="BT_site_engineering_code" title="BT site engineering code">BT site engineering code</a></li>

<li><a href="Speaking_clock#United_Kingdom" title="Speaking clock">BT Speaking Clock</a></li>

<li><a href="British_telephone_socket" title="British telephone socket">British telephone socket</a></li>

<li><a href="Cable_jetting" title="Cable jetting">Cable jetting</a></li>

<li><a href="Customer_Service_System" title="Customer Service System">Customer Service System</a></li>

<li><a href="Advanced_Mobile_Location" title="Advanced Mobile Location">Advanced Mobile Location</a></li>

<li><a href="Digital_Access_Carrier_System" class="mw-redirect" title="Digital Access Carrier System">Digital Access Carrier System</a></li>

<li><a href="Digital_Access_Signalling_System_2" title="Digital Access Signalling System 2">Digital Access Signalling System 2</a></li>

<li><a href="System_X_(telephony)" title="System X (telephony)">System X</a></li>

<li><a href="Redcare" title="Redcare">Redcare</a></li>

<li><a href="YouView" title="YouView">YouView</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:3em;text-align:left;background-color:#eee">Defunct</th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Digital_Access_Signalling_System_1" title="Digital Access Signalling System 1">Digital Access Signalling System 1</a></li>

<li><a href="Digital_Private_Network_Signalling_System" title="Digital Private Network Signalling System">Digital Private Network Signalling System</a></li>

<li><a href="Fixed-Mobile_Convergence_Alliance" title="Fixed-Mobile Convergence Alliance">Fixed-Mobile Convergence Alliance</a></li>

<li><a href="Go!Messenger" class="mw-redirect" title="Go!Messenger">Go!Messenger</a></li>

<li><a href="International_Packet_Switched_Service" title="International Packet Switched Service">International Packet Switched Service</a></li>

<li><a href="NHSnet" class="mw-redirect" title="NHSnet">NHSnet</a></li>

<li><a href="Packet_Switch_Stream" title="Packet Switch Stream">Packet Switch Stream</a></li>

<li><a href="Prestel" title="Prestel">Prestel</a></li>

</div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">History</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="BT_Group#History" title="BT Group">BT Group</a></li>

<li><a href="General_Post_Office" title="General Post Office">General Post Office</a></li>

<li><a href="Electric_Telegraph_Company" title="Electric Telegraph Company">Electric Telegraph Company</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Other</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="BT_Archives" title="BT Archives">BT Archives</a></li>

<li><a href="BT_Museum" title="BT Museum">BT Museum</a></li>

<li><a href="BT_Digital_Music_Awards" title="BT Digital Music Awards">BT Digital Music Awards</a></li>

<li><a href="BT_Sport_Action_Woman_Awards" title="BT Sport Action Woman Awards">BT Sport Action Woman Awards</a></li>

<li><a href="Buzby" title="Buzby">Buzby</a></li>

<li><a href="Connected_Earth" title="Connected Earth">Connected Earth</a></li>

<li>People</li>

<li><a href="Young_Scientist_and_Technology_Exhibition" title="Young Scientist and Technology Exhibition">Young Scientist and Technology Exhibition</a></li>

<li><a href="British_Telecommunications_plc_v._Prodigy" title="British Telecommunications plc v. Prodigy">British Telecommunications plc v. Prodigy</a></li></ul>

</div></td></tr><tr><td class="navbox-abovebelow" colspan="3"><div>

<ul><li><span class="noviewer" typeof="mw:File"><span title="Category"></span></span> <b>Category</b></li>

<li><span class="noviewer" typeof="mw:File"><span title="Commons page"></span></span> <a href="https://commons.wikimedia.org/wiki/Category:BT_Group" class="extiw external" title="commons:Category:BT Group"><b>Commons</b></a></li></ul>

</div></td></tr></tbody></table></div>

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