The New Jersey resident published detailed instructions online last week that he said will let iPhone owners abandon AT&T's service and join a competing cellular network.

The teenager's method, which requires a soldering gun, a steady hand and a set of software tools, is one of several techniques that have emerged to break the technological locks confining the iPhone to AT&T's network.

'This was about opening up the device for everyone,' George said in an interview over his iPhone using rival T-Mobile's network.

Network providers seek to keep their customers through multi-year contracts, which are expensive to break, or by using complex technological locks on phones to ensure that they run only on a given carrier's wireless network.

People who work on unlocking cellphones think those locks unfairly restrict customer choice and flexibility to use their phones overseas.

George says it took him about 500 hours to unlock two iPhone units. He put one of them up for sale on eBay, and bids have already exceeded thousands of dollars. The phone sells for US$499 (S$760) in an Apple store.

Neither Apple nor AT&T would comment on George's handiwork, or on another unlocking technique revealed on Friday by an anonymous group, iPhoneSimFree.

The group demonstrated its technique to unlock iPhones with just a software update. iPhone owners can presumably run that software and then insert another carrier's SIM card. They would still have to pay monthly fees to AT&T, however, until their contracts expire.

The six-member team plans to start selling its software to interested parties.

Bladox, a Czech Republic-based company, already sells a device called Turbo SIM which, when attached to another carrier's SIM card and inserted into an iPhone, works by convincing the iPhone that it is still running on the AT&T network even when it is not. The company has reportedly been overwhelmed by orders for the US$80 device.

The Library of Congress had ruled earlier that people can legally unlock their mobile phones. But the ruling does not apply to those who distribute the unlocking tools.

Apple and AT&T could sue George and iPhoneSimFree under the copyright Act. They could also argue that the phone hackers are interfering with their business relationship with customers.

Apple might also seek to block the unlocking tools with its regular software updates to the iPhone.

New York Times