Sign up for your free service at NOMOROBO.com. FIll out all info requested. They will then direct you to actviate their service back here on your My Verizon site under the phone services. They will then ask you to click a button that will ring your landline. Answer it so they know you are real and your number is real.
That's it. No more robo calls.
HOWEVER, scammers may still get through. I have one scammer I cannot stop that spoofs local numbers that are not in service.