Hi, I was having a hard time finding an answer to this. I purchase broken iphones and repair them for resale. I've had very good luck but just got a smashed iphone 4 that was reported lost/stolen. My Straight Talk sim card got blocked and it won't work anymore, and after talking to ATT and Straight Talk my only option was to get a new sim card and transfer my existing straight talk account to the new sim card (costed $15). Someone told me that this wouldn't have happened if I was with ATT instead of straight talk...but I also read online that ATT would block ATT sims as well. Does anyone know for sure whether ATT is blocking ATT simcards if you put it in a lost/stolen phone? I would feel real stupid if I end up getting a contract with ATT and have my sim blocked cause I need to test phones that I fix. Thanks for any help!