In the past two days alone, I've gotten over 20 spam calls with none of them leaving a message. Just 3/4 seconds of silence on my voice mail. One call the other day left a 22 second blank message.
I had to get a new number a couple of years ago. That "fixed" the issue for a long while.
I was able to get some cheap numbers on VOIP so now I give those out to businesses that require a phone number, so that I can kill them if the spam calls start up again. It helps quite a bit. I know some people also use Google Voice to emulate what im talking about.
Honestly, most people dont even call me anymore, they just txt or video call.