When the iPhone first released on June 29, 2007 there were lines of people in Mac stores across America waiting to be the first to pay $599—to touch its magical screen and make a phone call to a friend and scream “I got an iPhone!”
And there was another kind of person in those lines. This person could not wait to grab an iPhone, run home, and void their warranty immediately. Hundreds of developers, hackers, and power users were first in line to get their hands on an iPhone and start unlocking its full potential.
Since the first release of the iPhone people have been “jail breaking” and “unlocking” their iPhones by the hundreds of thousands. An iPhone that is “Jailbroken” can allow third party programs to be installed, such as games, karaokie machines, tip calculators, programming tools, and even a pretty stunning simulation of a guitar that could be played on the iPhone.
Other unique features of “unlocking” the iPhone include the ability to change settings in the phone, such as background images, sounds, and even the available service carrier.
In 2007 At a London Apple retail store where Jobs announced the iPhone's Nov. 9 U.K. debut, He responded to a question about whether Apple would put a stop to the unlocking hacks that have mushroomed recently. "It's a cat-and-mouse game," said Jobs. "We try to stay ahead. People will try to break in, and it's our job to stop them breaking in."
When Apple first learned of the hack they released an update that would render “unlocked” iPhones useless, turning them into very expensive paperweights.
The hacking community did not stay still; within a day they had already found a way around the new update and hacked iPhones were working again. With every update that Apple has released, the community has found a way to continue to get the perks from Apple’s update while having their phones unlocked.
According to cult-branding.com