People especially on the poor end of the spectrum can't not have a phone. A solution that only works if you have $100-$300+$600 per year per person is probably not a solution.

Any totally new solution is liable to be useful only to an increasing minority of the population over at least the next few decades.

It would probably be easier to graft authentication onto the current system and force individuals to post a tiny bond per assigned phone number.

Let people report robo calls and cause robo call originators to forfeit their numbers and bonds and don't allow them to buy new numbers under the same identity or credit card.

Even paying $10 per per 10 robo calls placed would boost the cost to $1 per call.

If you need 1000 bullshit calls to scam $500 out of someone then your net is negative.