AT&T charges me two charges. One for unlisted and one for unpublished. You could also be getting a computer dialing service that just dials random combinations of numbers.
On the Ringmaster number they know my name also so that's not random. That info should be with AT&T only as it is not a call out phone line but rather is simply a special call in number in addition to my regular land line. It gives a specific {different type} ring if that number is called. I've never used that number for anything on any paperwork and it would not and could not show up on anyones caller I.D. either.
Computer generated calls I'm used to as they generally are either recordings OR you will get a pause for a few seconds till an operator on the other end picks up. In other words the computer dials numbers and when someone answers it prompts a telemarketer to talk to you. Theres a company out of Washington State outside of Seattle doing some of the computer generated calls for credit card nonsense and I'd love to stop them.
I had my number changed a few years back for security reasons and told AT&T then I did not want any of my numbers made available to anyone but 911. In other words not released to the public without my consent.