Fire crews were called to a BT building in Newcastle on Thursday, July 23, after a fire alarm went off and staff reported a smell of burning.
No one was hurt and officers were able to identify the source and isolate some of the equipment.
Customers with broadband giants BT and TalkTalk were among those affected, with Newcastle, Gateshead and Sunderland listed as the most reported locations for issues.
A BT spokesman apologised to customers but the firm has not yet commented on the cause of the fire.
Talk Talk confirmed on Twitter later the same day that the problems had been resolved.
They said: ”The earlier issues in the North East of England have now been resolved. We apologise for the inconvenience caused during this time and appreciate your patience whilst we worked to get things fixed.”
A spokesperson for Tyne and Wear Fire and Rescue Service said on Thursday: “Earlier today, crews from Newcastle Central, Byker and Hebburn were called to a BT building in Newcastle, where an automatic fire alarm had activated and staff had reported a smell of burning.
"The crews identified the source and together with onsite engineers, decided that the safest course of action was to isolate some of the equipment.
"No one was hurt and smoke damage was minimal.”