Mobile operators O2 and Three have confirmed problems with their mobile network across the UK and said they are looking into the problems.
O2 has posted a message on its website saying it was aware of a problem with its “voice services” and apologising to customers. The company said their technical teams were continuing to investigate and working to resolve the issue.
Three UK has also confirmed that a fault with voice calls are affecting “around 3%” of users.
The problems have been reported as millions of people begin working from home as they follow guidance by the UK government to cut down on social contact to help prevent the spread of coronavirus.
Customers of all four of the UK’s major networks — EE, Vodafone, O2, and Three — have reported problems, according to network status monitoring website Down Detector.
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EE told the BBC it is something “that is affecting all operators and we are working closely to fix it.”
“We don't believe it is connected to the rise in home working,” said EE.
Vodafone told the BBC that it was a "short-lived problem" only affecting around 9% of voice calls on 3G networks.
A spokesman for Three UK said: “We are aware of an issue affecting around 3% of voice calls.
“We apologise for any inconvenience and our team is working to fix this ASAP. The rest of the network is stable.”
In a statement on its website O2 said: “Some customers may be experiencing issues when making and receiving voice calls on our 2G, 3G and 4G networks.
“Our mobile data and messaging services and O2 Wifi are not affected.
“This is a cross industry issue and our technical teams continue to investigate, working to resolve the issue as quickly as possible. We apologise for any inconvenience.”