Sometimes I'll answer & put them on hold just to waste their phone bill a little  or play mind games with them if I'm bored

It's always good to back up if the phone get broken!

I record regulars phone numbers and TW's. The black list list goes:

TW1
TW2
Indian TW
Irish TW
Idiot who stood me up 1
stocking twat
etc....

They all show up in my caller ID when they call. It's awesome cause they go directly to voicemail. But then some don't seem to get the message so they continue calling and calling and calling... If I called someone 10 times and left 5 messages and the person didn't contact me I would GET THE MESSAGE. But these guys don't. Deluded anyone?

pests!   

Dealing with this bull----t is part of the job so I don't let it affect me. But I use to work the phones and deal with the public in my civie job before and had to put with the same shit (or worse because the conversations were recorded and I couldn't just hung up). At least now I can.
 

Yeah I'd use the "ignore but don't actually say I never want to speak to them again let alone see them" method. There is a reason we don't want to speak to such people again let alone book them (usually because they have been pushy twats) and because of this pushy-twatness they are likely to change numbers or even don false accents to try and fool you into answering them again if you outright say never to call you again. If you don't actually say that their hope/delusion springs eternal and they never seem to change numbers or get the hint so you usually always know who is calling and who to avoid.

I had one very very creepy ( silence of the lambs voice he had   longest dragging hour of my life probably) persistent idiot finally manage to book me after I kept telling him on the phone I wouldn't see him and to stop calling. He changed numbers 4 times (!) and names twice and put on numerous false accents (yes really!) before finally getting me on an off day where I didn't recognise his peculiar speech pattern and whiny voice.   He was a horrid client, very creepy and caused trouble with the neighbours by shouting in the corridor outside when he was leaving because he didn't feel I had been affectionate enough 

I call them "timewaster 1, timewaster 2, " and so on.

As well as "rude", "arsehole", and "pest" to name just a few

i never forget a face tho!