So, at work our phones all have caller ID on it. When I get "Unknown External Number", it is 100% of the time someone trying to sell me something. So I don't answer those calls and instead screen them via voicemail. If it's a legitimate call (which has never happened), I'd call right back.
So, this assmuncher calls today. I have a screaming monkey for a ring tone, so I can't miss the call, but I let it go to VM. Said assmunch doesn't want to talk to VM, so he calls right back, literally within seconds.
So I pick up, hit a few numbers, and hang up.
He calls back.
I do the same thing.
And again. And again. Probably a few dozen times. Eventually, he got tired of it and stopped.
When I was out for a week, I came back to see literally dozens of missed calls from "Unknown External Number". These people suck.
But they'll call again tomorrow. If it wasn't for being at work, I'd use my patented string of profanities that usually stops people from calling me.