Keeps calling multiple times a day. At every hour. Won't stop. I'm on do not call list. Called the number back and is out of service. Spam Spoof call. Illegal harassment. These people will be sued.

Answer as:   Good afternoon, Federal Cyber crimes, may I help you.  Instant hang up!!

This number called me every hour. And if I picked up, no one was there! So annoying. But if you have an iPhone, you can block them! Settings -> Phone -> Calls-> Blocked - > Add New (just add them to your phone so you can chose the contact).
    
Then they can never harass you again.

I am getting this phone four times a day. when I call back, it is out of service. One time I took the phone and yelling out loud.
they hang out the phone. somehow they found my name and phone number .,

repeated calls  will not stop.....when you call the number back it is not in service.