British mobile phone company O2 said Thursday that thousands of its customers have been affected by outages on its network.

The company said it has restored service its 2G network and it expects to restore 3G service throughout the day, after problems blighted its network starting Wednesday.

“Customers who were affected should now be able to make and receive calls on the 2G network,” O2 said on its website, adding: “They may find it helpful to turn their phone on and off once.”

O2 said a fault in one of its network system at midday Wednesday prevent some mobile phone users from registering correctly.

The problem is not related to a specific location or range of mobile numbers, the company said, so the impact on customers was random.

“The fault is not related to signal strength or network availability from our mobile masts, which is why phones may still be showing full signal,” the company said.