This is pretty simple. We just don’t bother to answer the phone unless it’s someone we know. And they have to tell us who they are. My answering machine call log will store 50 missed calls. It is always maxed out.
I ditched my land line years ago as everyone I knew would call me on my cell phone number and all the calls I was getting on my land line were either telemarketers, even with being on the Do No Call List although that did cut down on them somewhat, or wrong numbers.
I have been getting calls on my cell from unknown numbers but I never answer them. If they don't leave a VM, it's a scam or telemarketing call.