Yes, as long as your with the same service provider. It also has free Wi-fi. Unlike the "Blackberry" you can just put in your old Sim card and it should work just as well.
as long as your new iphone isn't the iPhone 4,then yes.. you can use the sim card with other iphone
Yes, if it has no Simlock. If it has a Simlock, you'll need to Jailbreak/Unlock it first
Yes provided it is a used micro sim card.
The iphone 4 comes with a micro sim. Your normal sim will not work with it. My AT&T dealer says he can transfer data directly from your sim/old phone to your new iphone 4.
No!
Yes it can be swapped. I actually swapped my razr's sim card to my iphone. Nothing happened. It works perfectly.
No
If your 3GS is locked, you can't insert a SIM card.
CAN YOU PLEASE HELP ME OUT HERE..
Put the SIM card from the new phone into the old one. Copy the contacts from the old phone's memory to the SIM card. Put the SIM car back in the new phone - then - either copy the contacts to the new phone's memory - or leave them on the SIM card. Either way - the new phone will find them.
any AT&T phone that can take that sort of sim card.
No reason why not - the old SIM card should still work.
Yes, Yes you can.
You put a sim card in it.
Verizon doesn't have sim cards. Only AT&T.