Yes, they call nearly everyday, at least once, sometimes more, and leave no message; I finally became curious so I typed their name - their initials- into Google. Annoying!
How they got your number: First they called 347-000-0000. Then they called 347-000-0001. And so on. Eventually they got to your number. They just called me but I didn't answer. No message, of course. I'll block, but they'll just use a different number for caller id next time, probably.