Swapping Phones

I currently own a Samsung Galaxy Note II. My work pays my smart phone bill, but I got to choose the smart phone (and of course it's mine to keep).

I've given the Note II an extended test run and after months of trying to make it work, I'm interested in switching over to an iPhone.

What's the best way to "swap" my Galaxy Note II for an iPhone? I don't really understand how carrier differences and sim cards work. I know that I'm probably on the better end of the deal (more iPhone users looking to swap to a Note II judging by what I have seen thus far), but I'm not sure how exactly the process works.

Has anyone had experience swapping phones?

It would probably be best to check with your carrier. If they subsidize the cost of the iPhone and the Galaxy, you may be able to work a deal through them. I know that when T-Mobile introduced the iPhone 5 they had a trade program going. I'm not sure though what all was involved - cost, contract, and so on.