Numerous rapid-fire, dead-air phone calls. This was especially frustrating because they were anonymous and sometimes late at night. The voice mails piled up and prevented anyone else from being able to leave one. I called my carrier and they couldn't tell me the calling number. I finally looked at a detailed phone bill and there it was (this then allowed me to program the line to block that number.) I even tried calling it from another VOIP (disposable) number and I immediately started getting multiple anonymous, dead-air calls at that number. I found very little online, so hopefully this posting gives a little insight to the next poor soul to come in contact with this mayhem.