UK-based wireless carrier O2 doesn't appear overly worried about customers unlocking their iPhones, either. The company is aware of the growing number of consumers who use various hacks to make their iPhones work amongst competing carriers, but says the sheer number of handsets being sold is encouraging. "Demand has exceeded our expectations and we believe it will be the fastest selling mobile ever," a spokesperson for O2 said. "We've hundreds of thousands of devices to sell and we are extremely happy with how things have gone." British newspaper The Times cites O2 CEO Peter Erskine, who calls the iPhone the fastest-selling device the company has ever seen, and claims that sales are already in the "tens of thousands" since the Friday launch. Two-thirds of these are said to be for new O2 subscribers. Apple's iPhone sold out in almost every retail outlet that carried the device shortly after it hit shelves in the U.S., dwarfing sales of other handsets in the same time span and helping the Cupertino-based company to report another record quarter.