Cell phone upgrade programs?

I'm going to buy the iPhone but since is my firs time getting a plan i don't know much about upgrade programs. One of the main question i have is if i have to give my previews phone or do i get to keep it?

You aren't upgrading if you haven't had a plan before.

Depends on the carrier and the upgrade plan they offer. So check with the carrier you plan to go with what their upgrade plan(s) are, and how they work. They may have more than one, so you will need to find that out as well.

Don't think so in most cases. May be confusing upgrade programs to trade-in programs.