Despite the fact that it is possible to purchase an IMEI unlocked iPhone directly from Apple, the vast majority of iPhones are network locked. If you have a network locked devise, you can only use it with the carrier whose network it is locked to. In every country that Apple offer the iPhone, they have signed agreements to supply locked handsets to the major cell phone networks. So confident are the networks that they can recover this money, they will often supply handsets at massively discounted rates, on some occasions, even FREE, in return for a customer agreeing to a lengthy cellular contract. The networks have become some confident in the knowledge that they can and will recover this money of the length of a contract, that they are willing to provide customers with iPhones for mere pennies in some cases!
Buying a carrier locked iPhone for half the price of a regular iPhone sounds like it's a great idea? But what about if you have to travel a lot for business? Everybody know that international roaming charges can bankrupt you! There have been cases reported where individuals have been on vacation or overseas on business only to return to cellular bills for tens of thousands of dollars! A much cheaper option would be to use a local carrier and only pay domestic cellular and data rates. But only an unlocked iPhone can be used on any network.

Many hackers found the iPhone software unlock appealing because it was inexpensive and, with the right knowledge, could be applied pretty quickly. Despite the hackers best efforts, no sooner had they released their latest software unlock than Apple would release an iOS update to plug the exploit that enabled the unlock to work. It got to the point that by the time the iPhone unlocking software reached it final iteration there were reports of handsets completely freezing up, rendering the iPhone irreparably damaged, effectively becoming a paperweight - a state that came to be known as "bricked".

Anot