I would still find one prank phone call every six months annoying. I get that it's probably a small drop in what the poor people that unintentionally have that number deal with, but it's silly to think the readers would worry about the cost to the caller not the stranger called.
My number is unremarkable and I still get a half dozen spam/scam calls a day. An extra one in six months would go unnoticed. If you're not in my contact list, you go straight to voicemail.
We get that half dozen as what we call 'ghost calls' -- the caller has hung up by the time the outgoing message ends. It might have something to do with my putting SIT tones at the beginning of that outgoing message. If their autodialer doesn't drop the call entirely, it triggers their message, so we hear it start partway through; either way, we know not to pick up.