speaking of unlocks , iOS 8 has a new unlocking process!!! i found about it here just a month or so ago!
once you get the unlock from AT&T , all you need to do with iOS 8 is to insert a different carriers sim ( it doesn't need to be activated , meaning have service ) and the iPhone will automatically unlock itself
Power down the phone. Hold down the Sleep/Wake button and move your finger across.
Use the SIM card tool (or a straightened paper clip) to eject the SIM card holder from the side of the phone.
Remove the old SIM card from the SIM card holder. ...
Reinsert the SIM card holder into the iPhone.
power on
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if you can't get your hands on a sim card from a different carrier, then you have to do it the old way, and back up the iPhone to itunes, erase the iPhone , and restore it from your backup