okay so i just finished fixing my iphone i just downgraded the firmware back to 2.2.1 from 3.0. and everything works perfectly but it say it has no sim card, right. then i put my tmoible sim card in it and then all it does the no sim message on top left corner of iphone goes away and just the status bar shows and not the service name like tmoible. and is like i cant use it to call message or basaclly i cant do nothing with it just touch it, so if anyone knows how to fix this please message me quick and easy please!!!! 
HELP ME FAST PLEASE