On the heels of the grassroots U.S. effort “Operation Chokehold” comes word that the U.K. iPhone carrier O2 has crashed instead -- although the two events are unrelated.

According to the Telegraph, thousands of iPhone users on the O2 network have been unable to use their devices after the carrier’s network crashed for almost 48 hours. Users trying to access applications or the Internet were met with the message: “Could not activate cellular data network.”

“We are aware of an issue currently impacting data access for some of our customers,” a spokesman for O2 said. “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.”

The outage ironically falls on the heels of Friday’s efforts in the U.S. to bring down AT&T’s network, a stunt which seemed to only create a lot of media hype but little else. AT&T iPhone users have been quite vocal about dropped calls and slow 3G data almost since the handset first launched, but U.K. users appear to be mostly satisfied with O2 -- until this past weekend.

Many iPhone users took to Twitter and other social media websites to communicate that displeasure, including celebrities such as British actor Simon Pegg. One such tweet from a Briton named Meg Pickard summed up everyone’s frustration: “Having an  iPhone on O2 this weekend has provided a real insight into how we lived before mobile phones and ubiquitous connectivity. Bah.”

The outage was originally slated to be resolved on Sunday, but problems continued even into Monday afternoon U.K. time. It comes at a bad time for O2, after losing iPhone exclusivity there and now facing stiff competition from Vodafone and Orange.