http://www.unlockscodes.com/

Official iPhone at&t unlock Via iTunes
Send the IMEI to our server
Wait 1 - 5 hours we return the answer "activated"
Then, install last version of iTunes
Make sure phone is last version updated by official iTunes
Connect phone to iTunes with not accepted (not valid) simcard
Wait until itunes detect iPhone
Now diconnect iphone and reconnect after 10 seconds.
Phone Unlocked