Bought a Apple replacement device on eBay. Can they blacklist at anytime?

I bought a brand new, unactivated Apple store replacement iPhone 6s Plus. It is factory unlocked and no carrier SIM has been inserted or associated with it. Can the seller call and blacklist the phone after I pay him for it?

Actually yes, yes they can. At any time as long as they can show proof that they bought it, from Apple or a carrier, they can call and report it stolen. Several people I know have had this happen to them, due to the seller showing up at the place they bought the phone with the original sales slip to say they had been robbed and that their brand new phone, still in the box was one of the many items taken.

Will this happen to you? No way of telling, but if it were me, I would ask for the original sales slip, if the deal sounds too good to be true price wise, and if they said no, I'd walk from the deal.

ALWAYS as for the phone's IMEI or ESN up from so you can check it online AND with the original carrier.