We have an unlisted number too, which is why it always ticks me off when we get calls.
I had a funny conversation with a charity telemarketer who called and asked for someone else. When I told him he had the wrong number, he said, "Well maybe you can help" and proceeded to give me his spill. I told him I didn't give to charities over the phone because they have no way to prove their legitimacy. He told me I must have given to them before or he wouldn't have my number. I replied, "You don't have MY number. You asked for Mrs. Jones. You don't even know to whom you're speaking." He hung up.
Becky