How to use my iPhone 4 without a sim?

I'm not sure what the carrier is, but I can't get a sim for it any time soon and I just bought it. It's on iOS 7.0.2. I'm just trying to activate it to use it as an iPod, I'm not worried about the service.

You will need a sim to activate the phone. Borrow an active sim from a friend to activate it. Once that's done, take out the sim and you're good to go to use it as an iPod.

Yes you could, but only after you get the SIM required to activate it.