Yep..that's how I got my iP7+ last year. It was a hassle though...they had no AT&T phones and I was desperate to get rid of my Samsung phone so I reserved a verizon phone..they wouldn't let me purchase it without a verizon plan so I had to open a new verizon account, go through 2 credit checks, give money up front for taxes and whatever for both things and then go to at&t to get an att sim, and call verizon back to cancel the account. it was a pain in the ass and i'm not doing all of that for a phone again this year, LOL.
..i'll probably just end up selling one of the phones to pay off the installment plans and keep the other one LOL. Make a profit off these companies!