Guys my iphone 3g is carrier unlocked. Have this sim card(card 1) in the iPhone i has been working since day 1 but yesterday it started to have a problem the IPhone keeps displaying NO SIGNAL and it keep displays "NETWORK LOST your selected cellular network is not available......"but when i put this sim(card 1) on another sim(card 1) it works fine. and when i put in another sim(card 2) in to the iphone it works fine all signal is full. Something to add when i put in(card 1) the iphone is able to detect the celleur network but unable to connnect to it. HELP PLEASE