I've found that if I don't recognize the number, I answer the phone and don't say anything. If no voice comes over the line within 5-10 seconds, I hang up.
I have heard of these automated systems wait for a sound before it logs you as reachable for further annoyances.
If I do answer, I stay silent even muting my phone.
Usually call just hangs up.
I get the cruise every few months, from a spoofed local numbers.
As soon as I say hello, the automated recording went off.
I had a friend who liked playing around, and drafted fake PayPal confirmations and western union statements as proof he sent the scammers money.
They were confused why they didn't have his funds asking him to triple check recipient info and resend, which he would send another fake confirmation.
They would eventually catch on cussing him out after weeks
Isn't there a registry where you can opt to not be disturbed there? We have it here and I signed up, and calls eventually stopped. I also love terrorizing spam callers with "give me your name and company name, this call is illegal". They usually get flustered and hang up.