I just wanted to chime in because it seems everyone just ignored the post. There is a way to unlock your tilt without ever calling AT&T. All you do is go to xda-developers and there a person that has been kind enough to create a method to unlock the phone... and its free! Go to this topic
Kaiser Sim Unlocker - xda-developers and read about it. You might want to check out the other things jocky has done because he has a lot of great stuff. Its just another way if you don't want to call AT&T a couple of times.