They call several times a week - around 8:00 AM, which is illegal in itself, and after 9 PM.  Caller ID says "name Unavailable".  I didn't answer, they left no voice mail, so at first I thought it was a wrong number, until I've been getting these incessant calls.  I tried to block the number, but Vonage says it's an invalid number.  I did other searches, with the same results - invalid number. I don't answer these calls because even if there's just dead air on their end, it indicates that they've reached a working number.  No use reporting them to the DNC list, as this number cannot be traced,.  It's so frustrating, and I'm very angry that I can't do anything about it.