How to get a spammer to hang up on you...lol.

[MKLKT]

I've found that the trick to an auto-dialer is to only say 'Hello' once and then cover the mouthpiece or say nothing. If you do that, it will almost always hang up as it's expecting a person to say something twice which is habitual for people if they can't hear the person. If it's a legit person trying to call you personally, they'll already be active on the line.