I opened a new account at Claro (cellphone company at Latin America) and Bought a unlocked iPhone 3GS (from AT&T).. It was working just fine, until 3 days it stopped recieving any text messages. I can txt ANYONE and they receive it just fine, but i cant receive any text back.. after 4 days of trying to repair it I figured out that If I switch my SIM to any other Claro mobile then I receive all the messages I didn't recieved with the iPhone (a huge bunch of messages) at the same time. I need HELP I dont know what to do maybe is an Iphone bad configuration.. I dont know... I used http://repo666.ultrasn0w.com to unlock it.

Please any PROFESSIONAL RESPONSES would be really appreciated.