i have an iphone that was unlocked for use with t-mobile and given to me (i use at&t). It is operating on the firmware 1.0.2 and i tried putting in my att sim and it worked good fine just swapping sims. Is there anything I need to do in order to begin using it with att? If i hook it up to itunes on my PC will it brick? Any help, PLEASE!!! Thanks so much.