NEW YORK — The last summer before college is full of possibilities. George Hotz, a slight, curly haired teenager in Glen Rock, N.J., spent it taking on two of the largest corporations in the U.S. technology industry, and winning.

Along with a secretive group of online collaborators, the 17-year-old broke the restrictions that make Apple Inc.'s iPhone, arguably the hottest gadget of the year, work only on AT&T Inc.'s cellular network.

The feat took him 500 hours, or about eight hours a day since the iPhone's June 29 launch. The equipment used included a soldering iron and a large supply of Red Bull energy drinks.

An AP reporter verified that an iPhone Hotz brought to the AP's headquarters yesterday was unlocked. Hotz placed the reporter's T-Mobile SIM card, a small chip that identifies a phone to the network, in the phone. The phone then connected to T-Mobile's network and placed calls using the reporter's account.

Apart from AT&T, T-Mobile is the only major U.S. carrier that is compatible with the iPhone, even an unlocked one, but an unlocked phone would work with most overseas carriers.

"That's the big thing," said Hotz, who heads to college today.

Apple has said it plans to introduce the phone, which combines an innovative touch-screen interface with the media-playing abilities of the iPod, in Europe this year, but it hasn't set a date or identified carriers.

AT&T Inc. spokesman Mark Siegel and Apple spokeswoman Jennifer Bowcock said their companies had no comment.

INFO NOW OUT THERE

The hack is complicated and requires skill with both soldering and software. Missteps may result in the iPhone becoming useless, Hotz warned. It takes him about two hours to perform and he's posted the instructions online.

Since the details are public, it seems likely a small industry will spring up to buy U.S. iPhones, unlock them and send them overseas.

"That's exactly, like, what I don't want," Hotz said. "I don't want people making money off this."

He said he wished he could make the instructions simpler, so users could modify the phones themselves.

"But that's the simplest I could make them," Hotz said.

Technology blog Engadget yesterday reported successfully unlocking an iPhone using a different method that required no tinkering with the hardware.

The software was supplied by an anonymous group of hackers that apparently plans to charge for it.

STILL MORE

The iPhone has already been made to work on overseas networks using a third method, which involves copying information from the Subscriber Identity Module, a small card with a chip that identifies a subscriber to the cell-phone network.

The SIM-chip method does not involve any soldering, but does require special equipment, and it doesn't unlock the phone — each new SIM chip has to be reprogrammed for use on a particular iPhone.

The hacks leave intact the iPhone's many functions, including a built-in camera and the ability to access Wi-Fi networks. The only thing that won't work is the "visual voicemail" feature, which lists voice messages as if they were incoming e-mail.

LEGAL EXEMPTION

Since the details of Hotz's hack are public, Apple may be able to modify the iPhone production line to make new phones invulnerable, but there is apparently little legal recourse for the company.

Last year, the Library of Congress specifically excluded cell-phone unlocking from coverage under the Digital Millennium Copyright Act. Among other things, the law has been used to prosecute people who modify game consoles to play a wider variety of games.

Apple shares rose $4.23 to close at $135.30 yesterday. AT&T shares gained 26 cents to close at $40.36.