You can buy an off-contract iPhone 5 from AT&T. It will cost you a lot. You may also want to unlock it. This will take you some time if you follow their instructions, which, according to TechCrunch, involve filling out an online form and faxing AT&T and finally waiting a week to hear back.
There’s a better way. All you have to do is restore your iPhone in iTunes. this will unlock the handset. TechCrunch has already been able to confirm this through AT&T tech support and were able to pull it off with a T-Mobile SIM.
Here’s a portion of the repot:
After receiving the notification my new iPhone was unlocked, I cut a micro-SIM card into the shape of a nano-SIM by using the AT&T SIM card that was already in the iPhone 5 as a guide. The most difficult part was to make it narrower so that you can close the tiny nano-SIM tray, though some have reported that this step may be optional.
In a couple of seconds, the iPhone was able to pick up the T-Mobile network, and calls and EDGE data connectvity worked as expected. Some reports, including on AT&T forum, confirm this.
Yeah. Now the problem is trying to cut down that SIM. Romain Dillet was able to pull it off, but it seems like it can definitely be a challenge that some aren’t ready for.