No clue who it is. Probably some scam like most numbers. You can download and app called Mr. Number to hang up on calls or send to voicemail. It works great!
I received a call from 515-700-0000. I am a teacher and had a class. When I had time to google it I found out these people are scam artists. I live in the Dallas area and I have been hearing of stuff like this happening around us.