I know this topic has been discussed a lot. It is my understanding that SIM cards can be swapped between phones, replacing a SIM card from Phone A with a card from Phone B allows all of the contacts and incoming calls from A to instead be on A. My question is this: does the phone know what SIM card is in it? What I mean is does it know what contract it is attached to. Here is why I ask. I am thinking that Apple will just sell the phones and the SIM cards seperate in the stores. This way if you have a contract you can just buy the phone and pop your card in. If you don't you would need to buy a contract to get the card and have a working phone. I know this has been discussed a lot. I am just curious though what current phones do... Would this be practical?