These @ssholes have changed numbers.  I don't answer calls with area codes and numbers I don't recognize, but this one leaves a message.  This is a robocall that is nothing but static, with voices in the distant background.  

Called the number back.  It's a campaign line, it also will activate the do not call list for your phone number

Call every day will not leave message.

Keep getting this call!  Then  they just hang up!