Hundreds of thousands of BT customers lost access to their broadband and home phone services following an outage on Monday (October 3rd).
A power failure at a major exchange in Birmingham saw around five per cent of the broadband provider's subscriber base affected.
Business users in particular were badly affected by the outage, which occurred at around 13:00 BST.
A BT spokesperson said: "We can confirm that, as a result of a power failure at one of our major exchanges, some customers may have experienced loss of broadband service for a brief period.
"Some business customers' broadband service may have been affected for a slightly longer period."
The spokesperson confirmed that all services were restored by Monday evening, with the majority of BT's consumer broadband customers' regaining their connection within an hour.
As of May 2011, BT had approximately 5.7 million broadband customers in the UK.