Is it possible to design a phone system that would prevent spoofing?

Keeping your phone on silent solves that problem.

A simpler alternative would be to just not own a phone. That way one would never be bothered. Not a practical solution for me however. Any more than never receiving any incoming calls would be.

One thing I do: If you call my phone, you’d better be ready to start talking when I answer. If I get even a second of silence first, I hang up.

If what you have to say is important enough to bother me at home, it’s important enough for you to manually dial my number. Anyone using an autodialer is someone I really don’t need to listen to.

But a microtransaction woild fix the problem. The fact that the problem hasn’t been fixed for decades tells me the phone company wants it this way.