Hotz, a recent graduate of Vocational and Technical High School in Hackensack, N.J., says he spent at least 500 hours working on the hack.
He recently told an Australian tech site that he began tinkering with the iPhone because "he needed a summer project," adding, "and wouldn't I look cool walking around with a T-Mobile iPhone?"
Hotz, who says he began programming when he was five years old, leaves this weekend for undergraduate studies at the Rochester Institute of Technology and will be majoring in neuroscience, or "hacking the brain," as he likes to call it.
The projects in development he lists on his Web site include a homemade electroencephalograph, or brain-wave reading machine that communicates with a computer.
"With mere thought, I can write words on the screen, turn lights on and off, or control a [video] pong paddle," Hotz says on his Web site.
The teen hacker counts among his heroes his dad, a systems engineer, as well as Apple co-founder Steve Wozniak. He hopes to land an internship next summer with tech juggernaut Google.
"My friend is doing an internship there and says it's awesome," he said.