Telecom group BT has been fined £800,000 by Ofcom for failing to provide an improved text-to-voice service.The so-called "Next Generation Text Service" is aimed at helping customers with hearing or speech impairments to have more natural conversation by using speech as well as text on PCs, laptops, tablets and smartphones.In October 2012, the telecom regulator told all UK landline and mobile phone providers to launch their service by 18 April 2014, but BT launched its service only in September last year, after missing the deadline because of technical problems with the sound quality of emergency calls.In June last year Ofcom launched an investigation into the delay relative to the implementation of the service and found that the problem became apparent only just before the deadline, while BT claimed the incident was a one-off.However, the regulator added that the mobile and broadband operator had 18 months to meet the desired requirement and failed to act for five months after the deadline had passed."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," said Claudio Pollack, Ofcom's consumer and content group director.He added that BT had now launched an improved service, and Ofcom welcomed the fact the service was now operating successfully.BT shares were down 1% to 447.08p at 11:19 on Tuesday.