My VOIP phone supports nomorobo. This service is awesome!
The phone rings once to let you know the call comes in, then stops ringing. Initially, we had 10-15/day but over time even the robots got tired of hitting this wall. We get one a day tops.
As far as robo calls getting through... in the last year we had one scam call that was calling ever 20 min that was not blocked. I reported it and blocked that number... never again.
faz