I don't know who this is but for several reasons, I think it's a robo-political call : 1) I have been tracking nuisance calls for several years, and there's a certain pattern/timing to these calls; 2) I have two lines, each only one number apart at the end and the call came across on one line, and then the other one in sequence; and, 3) It's a call from a new number (politicos purchase new numbers for campaign purposes), and 4) It's that time of the year.  

I called this number and it says that they are not available.  After I called this number they started calling me every 20 minutes.  So far 4 times today.  when they call - I have answered and they hang up on me.  After I answered the phone twice - the calls started coming in every 20 minutes.  I can not find out whos number this is.  I have tried all free avenues.

This number is calling our home up to 7 times a day.

non stop calls from this number

Went to voice mail did NOT leave message