I think this is what happening now a days, when a lot of people opt for "do not call list." DH number and mine are both (a long time ago) included (because I added them) to the list. Well, so far, when I get a call from numbers that I do not recognize most poster online say's that their numbers are listed under "Do not call list."
And how in the hell they get the numbers? In my opinion, this list does not work or simply, the company who own it sells the phone numbers listed. One other way is, when we give away our phone number to banks, stores (online or not), insurance companies, or when using it while doing some other transactions. I think those places are associated with some other companies, and shared their customers phone numbers.
I really don't mind them calling, but the worst part is, no one even bother talking at the other end. They hang-up all the time. Some numbers will call about four times a day.
I hate 503-902-8287, 812-962-4304, 509-209-3324, 503-457-1274, 603-856-0995, 253-208-4682, 503-468-5227, 800-445-4659 this is Appleby Window, I told them many times not to call because I am not in the market for window. Do they listen? A big fat NO! 212-375-0323, 630-256-1990, 832-405-6947, 425-390-8126, and some more. I blocked some of them through my carrier and can never get to me. However, I'm only allowed seven numbers to blocked. That's why these numbers always get to me.
They are all annoying!