Although developed by BT, the upgraded service is offered by all landline and mobile telephone providers and is also accessible on smartphones and tablets via a dedicated app.
It was due to launch last April but was delayed until October after testing revealed problems with the quality of emergency calls.
Telecoms regulator Ofcom has accepted that the problem only “became apparent late on” but says the firm had 18 months to deliver an improved service and did not do so until 5 months after an agreed deadline had passed.
As a result it has levied a £800,000 which will be passed on to HM Treasury.
Claudio Pollack, Ofcom’s Consumer and Content Group Director, said: “The size of the penalty imposed on BT reflects the importance of providing an improved text relay service to its customers with hearing and speech impairments.
“However, BT has invested significantly in launching the new text relay service, which allows users to have conversations more easily and fluently and on new devices. We welcome the fact the service is now operating successfully.”
