I had to start blacklisting phone numbers by the dozens to get any peace. I'm always hearing someone asking for someone I've never heard of and even if you manage to tell a human that you've never heard of that person and that this is your phone number and the person they want will never, ever be here, the debt (and your number) will just get passed to the next batch of collectors and the cycle will continue ever onward.
I can't count how many random bogus legal threats and whatnot I've gotten for someone who I don't know.