In my state, anyone can go to county records and see the information on who owns a house. The names will be there. Then from there they can try to find your phone if it is open listed with the phone carrier.
Good for you! Got calls from these a holes too. So I pressed *67 called them, on hold for 20 mins., then got "transferring your call", then got "goodbye"
What gets me is the lack of [***] government regulations! And I have an unlisted ph number!
Good job. If I am in the mood I'll answer with my best accent matching that of the caller. After a couple of laughs to myself and from my kids, and head shaking from my wife (I married this guy, lol) I close with "have a good day".