Three has advised customers suffering from a service outage to turn their phones off and on again, as it continues to try to fix technical difficulties with its network.
Many UK users of the Three network have been unable to make calls or receive messages since Wednesday night.
The mobile operator confirmed on Thursday it was investigating the problem, but has now issued additional advice to users, as parts of its service begin to return.
“Following technical difficulties with our services across voice, text and data, some customers will be experiencing an intermittent service,” the company said.
“Our engineers are working to fix the issue and the service is returning to normal, and we expect it to be resolved over the course of the day.
“We advise our customers to turn their phones off and on or turn airplane mode on and off, which may resolve the issue.
“We are sorry for the inconvenience caused to our customers.”
As well as its mobile network, on Thursday morning Three’s website was also unavailable, instead displaying a message which said it was down for “essential maintenance”.
That has since come back online and now also displays a message which reads: “Our services are coming back online. If you’re still having problems, please turn your device off and on again to get re-connected.”
The company has not yet disclosed the cause of the problem.
The incident came on the day another mobile operator, O2, became the latest to begin the rollout of its next-generation 5G network.