KCOM was today slapped with a £900,000 by regulators after dozens of people were unable to get through to the emergency services in a four-hour period.
On 28 December 2015, the London-listed firm that operates the majority of Hull's telecoms infrastructure failed to connect 74 calls to 999 or 112 numbers.
Ofcom found KCOM was in breach of rules stipulating the firm should ensure everyone can contact emergency services at all times.
KCOM said the outage was due to flooding at one of BT’s telephone exchanges in York, in the wake of Storm Eva. The regulator's investigation found all emergency calls from customers in the Hull area relied on the flooded telephone exchange in York.
Ofcom added KCOM should have been able to automatically divert 999 calls via back up routes. KCOM did, however, have alternative connections in place within two hours of identifying the problem.
Shares in the firm edged down 0.27 per cent following the announcement.
Gaucho Rasmussen, Ofcom’s enforcement and investigations director, said: "Today's fine serves as a clear warning to the telecoms industry that it must prioritise access to the emergency services, no matter what the circumstances.”
A spokesperson for KCOM said: “We recognise the critical importance of providing our customers with uninterrupted access to emergency call services and take that responsibility extremely seriously.
"During Storm Eva in 2015, the loss of our 999 service was a result of a single point of failure in another operator’s exchange in York. Our emergency call services are managed through long-standing external outsourcing arrangements. In establishing them, we sought to ensure diverse and resilient routing, which Ofcom has acknowledged in its findings.
"We’re very sorry this happened and immediately after the incident we ensured steps were taken to remove this network vulnerability. Customers trust that our service will be available in an emergency – and so they should.”
In June, Three mobile was fined £1.9m by Ofcom for emergency call failings.