i have tried to put my sim card in the other cell phone (silver razr) which the phone is from at&t...my brother said he did it before and it worked and he texted people fom it with my sim card in it but i wno't work for me....& YES i am putting the sim card in correctly!! ....everytime i turn it on it comes on then says "please contact your service provider" or somethin like tht but i don c why it's sayin that 4 me when i worked for ma brother like 2 days ago!! well help me the hell out