will a 3gs sim card fit into a 4gs phone?
can i put my 3gs sim card into a 4s iphone?
iPhone 3GS
No. The iPhone 3GS uses a standard SIM where the iPhone 4S uses a microSIM. It is possible to cut down a standard SIM, but that often causes problems, so it would be best to get a microSIM from your cell carrier.
Regards.