System Y

System Y is a Digital telephone exchange system used by British Telecom as an alternative to the System X. System Y refers to the AXE 10 system manufactured by Ericsson.

British Telecom decided to use the AXE10 digital telephony switching solution in the mid 1980s as a way of preventing total reliance on GEC (as it was at the time) System X as sole switching solution. This also meant GEC could not use a position of dominance as a way of charging BT unfair amounts for provision of System X equipment parts. Although System X is more abundant in BTs network, AXE10 is still widespread in Britain.

AXE10 covers two main types of digital telephony switching equipment - the RSS (Remote Subscriber Switch) and the AXE10 local switch. The RSS deals with the conversion of analogue telephony signals used in the access network (the copper pairs between exchange buildings and customers' 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 is coming up to its twentieth birthday) is maintained 'in-house' by its own engineers although Ericsson still provide high-level support, software upgrades and repairs at component level.

Both System Y and System X are likely to be phased out as BT implements its 21st Century Network based on VoIP and replacing existing switches, ADSL and analogue equipment with fully digital Multiple Service Access Nodes (MSAN).