get a call from this number almost daily

Got a call they said nothing

We get three or four such calls daily, even on weekends.  When we see "Ohio call" or "Florida call" we let it ring and if it's important we feel whoever it is will leave a message.  Occasionally if I'm annoyed I'll punch the "Talk" button and then immediately the "Off" button to stop the ringing.  Screw 'em if they don't want to leave a message.

Called this number back and it is a "special offer for home warranty". Anyone know how to get them to stop?

They have been calling at all different hours of the day and night, Monday thru Saturday.  
When the machine picks up, they hang up.. WILL NOT leave a message!  
I am registered with the State & Federal Do Not Call Registry, yet they still get through!

NEXT TIME, I WILL ANSWER AND THEY SHALL BE SORRY THEY CALLED SO MANY TIMES!!
I will definitely leave them 'a message'.  
I consider this harassment by communication at this point.