Apple iPhone Upgrade Program

I plan on upgrading my iPhone from the 7 to the XR or maybe an 11. I have a question about upgrading through Apple though. Do the phones come unlocked?

Yes: pick a carrier and it comes unlocked.

I was playing around with the pre-ordering system and thought it odd that the iPhone Upgrade Program doesn’t let you do a trade-in at the same time the way the iPhone Payments Program does. I may have missed something.