QUESTION: Can I Sell My iPhone 6 Plus That is On AT&T Next?

I no longer use my iPhone 6 plus, but it is still on the AT&T Next plan. From my understanding, if a phone is on this plan and is given to another person, the monthly plan fee will become a part of their account. Is this true?

Even if I sold the phone, I would be perfectly fine with continuing to pay the monthly fee associated with that phone.

Does anyone have any advice on how I can still sell this phone without having to do the device pay-off? Perhaps I could sell the phone online and then use those funds to do the device payoff. That should be enough time for the phone to register as paid, as it is in-transit, and then the buyer won't incur any monthly fees.

Thanks.