Robocalls I assume are profitable to someone. Therefore they will always find a way around blockage.

I have noticed most calls I get, the phone rings I answer, there is silence for a few seconds (maybe just one) where the robocaller detects someone answering the call, then they route it to a human. The human then gives their speal. I will do one of two things:

1) Say "hello, oh yeah I would like that" and then put the phone down near the TV.

2) Just hang up.

If I think it is a SCAM I will usually say something like, "you should be ashamed of yourself".

All in all, option #1 tends to work the best. I am now only getting "Extend your car warranty" call every 6 months.