The switch-off has come, according to BTW, as the traditional networks are no longer cost efficient to run and network suppliers no longer produce the replacement equipment needed.
Public sector organisations are thought to make up at least a third of the remaining customers using the services of which comprise about 9,000 circuits for analogue and Kilostream and 60,000 lines for Featurenet.
Clive Quantrill, BT’s enterprise migrations director, said: “Technology has shifted away from traditional telephone and data networking services delivered over copper networks, in favour of faster, more reliable fibre networks and digital IP services.
“Whilst the majority of our public sector customers have already migrated across to these new services in advance of our legacy products being switched off, a significant number have yet to take any action."