More than a quarter of a million people have purchased Apple iPhones and unlocked them, the handset's manufacturer admitted last night.

With total sales of the phone now topping 1.4m units, according to Apple, that's a staggering 18 per cent of buyers who've chosen not to tether themselves to AT&T's cellular network.

It's no great surprise to learn that the iPhone experienced a significant sales hike immediately after Apple cut the price of the 8GB model from $599 to $399 and began selling off its remaining stock of 4GB models - now discontinued - for even less. Most of the unlocked were sold after the price cut.

During Apple's most recently completed quarter, the iPhone accounted for 1.9 per cent of the company's revenues. The deal with AT&T involves sharing data and service revenue, but accounting complexity hides exactly how much money Apple received from the carrier - the cash is recognised "over time", Apple said and would say no more.

Apple yesterday reiterated its plan to sell 10m iPhones during the handset's first year, so unless it really does manage to lock out the unlockers - the latest firmware, 1.1.1, tried and subsequently failed to do so - and overseas buyers follow the example of US consumers, the company could end up with 1.8m iPhones running on other networks.

Indeed, with Orange France committed by law to offering unlocked iPhones and to unlock iPhones, at the buyer's request, after six months, the figure could be much higher.