If everybody would just make sure you have no background noise going on then pick up before it goes to voice mail then hang up without saying a word, maybe the callers would think it's not a working number. If you say "hello" or let your voice mail answer, then they KNOW it's a working number and you will be called over and over again. This is what I've started doing and will continue to do with these kinds of calls.
Modern technology has given telescammers the tools to call you.
Since those telescammers are criminals, they ignore both the Do Not Call list and any request you might make.
Modern technology can also protect you, if YOU do a few simple things!
The first thing to do is buy a call blocker device, service or app.
Then, use it correctly.
Google "call blocker" for more information.
If you cannot afford or use such a tool, then:
* Do not answer calls from unknown numbers ... let them go to voicemail or answering service
* Do NOT return calls from unknown numbers! All that does is verify your phone number! And, in some cases, those return calls may cost $20 or more to complete.