I'm confused, why do you have to finance if you want a ATT phone from Samsung and not a unlocked?

[pags11]

Are you allowed to pay it off in full when you get your first payment? Question: If I get the unlocked version will I be able to pull my ATT sim card out of my S10 (ATT branded) and put it into the S20 Unlocked and it will just work? In the past I always got new sim cards for new phones but I was wondering if could just put my current sim in and have it work without getting a new one.

It is my understanding that you will be able to do that with your SIM card, yes.