What to do with an iphone 6s plus i got in my mail?

I got an iphone 6s plus in my mail today and i never ordered for an iphone, never entered any competition to win one and i also never filed for a lost device through an insurance company, I DON't EVEN HAVE INSURANCE ON ANYTHING. I just opened my mail and found an iphone 6s plus in there… Brand new… And it seems to be sprint locked. On the stamp… The mailing address is correct but only my first name is on there, my last name isn't on there, do i give it to the police or call fedex or what?

You should try to call sprint and ask