What does it mean when it says sim card free when buying an iphone 4s onAmazon n?

I'm trying to buy an unlocked white iphone 4s on Amazon and it says unlocked and sm card free. So does that mean I can enter any Sims card, or it doesn't have a slot were i can put one in? Or do all iphone 4s have a sim card slot, but certain networks i can't use? Because i have a t-moble sms card

It means you have to get your own SIM card to use it with a GSM carrier. You can ask your carrier for one.

I think a sim free means it is a CDMA phone, not all iphone 4S's have sim card slots, you need to ask the seller to be sure. It sounds like it could be a verizon/sprint phone.

It should mean that the phone is unlocked and any sim card may be used in it.