What is the best app to block robo-calls?

Question

The National Do Not Call List is a joke and scammers are running wild trying to convince me that the cops are coming by any day now to arrest me for various crimes, someone at the IRS is VERY angry with me over some tax bill that has gone unremitted for some time now. I want them to go into a blacklist hole and straight to the trash. Can you help?

Meir Cohen · Accepted Answer

It is the only app that not only blocks the spam callers but also turns the tables of torture on the annoying callers. It records conversations of the clever bots tormenting the evil telemarketers to give them a taste of their own medicine.

Shivek Khurana · Answer

It has a huge global database and accurately identifies spam calls.

dan leatherman · Answer

This is a great app for iOS and android.

Kesava Mandiga · Answer

Works well, for the most part. Might annoy you with all its notifications and pop-ups though.