Here in the UK ever since the iPhone has been available, once your device is out of contract the mobile carriers are required to unlock your device if you ask them, although the process is less that straight forward.
Now US mobile carrier will unlock your iPhone on their network if your contract has finished, something which iPhone users on AT&T have been asking the company to do for a long time.
You can now either request AT&T to unlock your iPhone in a store or over the phone, the only information they need to do this is the IMEI number of your handset, the process takes up to 72 hours, and during this time Apple pushes the unlock code to your email address that is associated with iTunes.
The device can then be unlocked by connecting it to iTunes, and you can find out full details ob how to do this over at Apple’s support site. Apple has now announced the iPhone 5, have a look at our article on the difference between the iPhone 4S and iPhone 5 to see all about the new iPhone 5.
Source The Next Web