I found this post on a method to unlock the ATT GN2 for free. I did it and checked it with my wife's t mobile SIM and it did work just fine! It took several minutes for the T mobile network to come on but it did. Save yourself a few bucks.
Free UNLOCK N7105 - xda-developers
This is awesome news. Does anybody know if this is a permanent unlock that can't be undone? (ex: a software update might re-lock the phone)
Thank you !
How do u get to unlock screen and code