Sign up for No More Robo.com. It is the best call blocking service and it is free you just have to sign up on their website.
I believe it is Nomorerobo.com. I've had it for over a year and it is outstanding!
It also does not let telemarketing and robo calls thru, your phone will just ring 1 time and the number is blocked from ringing.
I hope this helps you. I believe you can only block 12 telephone numbers with Verizon Fios.
If nomorerobo blocks a number by error all you have to do is go to their website and log into your account and correct it there.
Obviously depends on hour plan. FIOS Digital Voice includes blocking for up to 100 numbers. And NoMoRobo services works with it.
My Cell phone includes its own blocking.