Really annoying.  And don't answer when you try to call them.

My estranged father, over 10 years, recieved a call at his house, to which I don't even have the number.  He emailed me saying the left a message asking for me, but when I called them, they had no record of my name in their system.  The lady who answered the phone, Crystal, was very rude, and when I asked for an explaination of how they had my fathers number as my number (when I don't even know it), she said she had no idea what I was talking about, and that it must not have been the number on his caller ID; that he must have emailed me the wrong number - actually asked if I saw it in person (although I explained that I live in AZ and he lives in Ohio).  When I asked her first and last name, she hung up.

They keep calling my cell phone and when I try to call them back to see who the number is they never answer. Very annoying

They called and said asked if I could verify my address.  I said I would be happy to help them once I learned the nature of their call.  They refused to say why they called and I hung up.  THEY ARE JERKS.

They called my cell phone and did not leave a message.  When I call back, it just rings and rings and rings. I am registered with the "DO NOT CALL REGISTRY" and will report this should it happen again.