BT has been fined £17.5m for a “catastrophic failure” of its emergency call handling service which led to to thousands of 999 calls not being connected.

The network fault, which last lasted for more than 10 hours on 25 June last year, led to 14,000 calls to emergency services failing to connect.

Following an investigation into the company which manages the 999 phone system, the regulator Ofcom said the telecoms giant was “ill-prepared” to respond to the problem.

“BT fell woefully short of its responsibilities,” said Suzanne Cater, Ofcom’s director of enforcement.