Buying a new phone

Not necessarily...

Apple acts as an agent for all of the major carriers. All of them have 'payment plans' one can sign up for at Apple. In that case, the purchase is actually being made from the carrier with Apple acting as the agent. Not really any different from going into Best Buy and buying a phone on contract from a carrier.

Well, except that the sales person you're talking to actually has a clue, as opposed to Best Buy...

I purchased my Xr at my local Apple Store using AT&T Next.

If you make your purchase at Apple, and they set up monthly payments, then you are paying Apple, not your carrier.

True, I forgot that they have the ability to work as agents for the carrier. However most of the time when a trade in is used, or the latest advertisement they show on the iPhone page, I believe is financed through Apple. And, the iPhone Upgrade program is financed through Apple's financing. So the real answer to the question is that it would depend on what program the OP chooses at the time of purchase.