I have no idea who this is .. I got already 3 calls for them.

THe call is from Congressman Raul Grijalva.

Keep getting calls from this number, but I do not answer it

I am tired of receiving these type of calls, no one is on the line they are just calling and hanging up.  Also you cannot call back the phone company recording says the number does not exsist.  What is this and why do they keep calling , perhaps its a customer care caller just trying to get credit for the number of calls.  But they are often, many days in a row.  And its very annoying.  What can I do to have this stop.