This caller showed up as coming from 13-172-1100 on my home phone. A few minutes later they tried to call back, but I had the call forwarded to my mobile at that point when it came through as (317) 211-00. Yes, a non-10 digit number. I'm guessing this was a VoIP initiated caller using spoofing technology.
It looked like a scam so I did not answer. No voicemail was left. (hung up on the 3rd ring.) Only called twice a few minutes apart.
apparently both Vonage and AT&T are not cross checking for valid caller ID information as a tool to block scam calls. I'll be taking this up with both companies.