A few years ago I got fed up with the scam calls and even worse, scam voicemails if i denied the call. I started accepting scam calls and immediately muting my mic. The line stays connected and usually silent from 15-40 seconds and then disconnects.
The amount of scam calls I received went from several a week to a few a year. I've had two so far this year. It's possible my number is being marked as non-working.