I personally like Google Voice call blocking. Blocked callers get a nice DISCONNECTED message if the call my phone again :) In addition some robocall systems will flag this as a bad number and take it off their list!
This number called me today. They stayed on for about 5 seconds and hung up. I called the number back and it just rang and rang. My phone identified it as a VOIP caller
Just received a call from this number, which I didn't recognize, and the caller ID said "VOIP call."
I immediately called the number back (blocking my number first), and it just rang, and rang. Since not even two minutes had elapsed since they called me, and I called them back, you know this is just another scammer. Block!