O2 services restored following overnight downtime

O2 is asking customers to turn their phones off and on again in a bid to restore lost voice and data services.

The company said its 2G network, which handles calls and text messages was now working, adding that 3G services for mobile internet would be restored throughout the day.

Mobile phone customers have been experiencing problems with voice and data services since yesterday afternoon, with O2 reporting a fault at 16:45 on Wednesday. It wasn't until 01:00 Thursday morning that O2 identified the cause of the fault.

"We can confirm that the problem with our mobile service is due to a fault with one of our network systems, which has meant some mobile phone numbers are not registering correctly on our network," O2 said in an update.

"Customers affected may wish to try switching their mobile phones off and on as service returns."

Last year O2 suffered two network outages. In February some customers had problems sending texts while in May the network went down for 16 hours.

Users of Tesco Mobile and Giff Gaff services, which rely on O2's network, were also affected by the fault.