O2 has admitted it's been having faults on its data network once more, leaving thousands of customers without internet access on their phones.

We spoke to O2, who declined to comment on the reasons for the outage, but did confirm it wasn't a problem with capacity on its networks.

UPDATE: O2 has been in contact again, giving a little more insight into why the problem occurred (although it probably won't mean much to most people):

"We are aware of an issue currently impacting data access for some of our customers. We have identified a fault with the allocation of IP addresses and are working to resolve this as quickly as possible. We apologise to any affected customers."

Data failure

Anecdotal evidence currently suggested that the problem is contained within London, and given the density of data-loving customers, this would obviously inconvenience a large portion of customers.

However, O2 has also (somewhat mysteriously) told us that this problem is "not geographical" - so we have very little idea what's causing this problem.

O2 data outages over the past year have been well publicised, mostly due to the large portion of iPhone users on its networks, although this data failure isn't just contained to that one phone model.

We're awaiting further information on the root of this problem (we're hoping it's something fun like mice chewing through wires) but don't worry - we're assured it's not going to be a Christmas wrecker.

UPDATE 2 [29 December 2009]: O2 has today apologised again, this time in an article in the Financial Times. Despite O2 previously denying to TechRadar that the problem was due to network capacity, Ronan Dunne, head of O2, now says that the issues with the London network were caused by an "explosion" in demand for data from bandwidth-hungry smartphones.

To address the problem, Dunne said that O2 is working on its infrastructure to improve the management of voice and data traffic on its network; that it would be installing an additional 200 base stations in London; and that it is talking with handset manufacturers including Apple and RIM in an effort to better understand the demands that smartphones place on a network.

"Where we haven't met our own high standards then there's no question, we apologise to customers for that fact," Dunne told the FT. He described the problems as a "short-term blip."