That doesn't solve the problem where legitimate numbers are spoofed, does it? It seems my number is among the many that are being used by robocallers, because I sometimes get texts from strangers saying "who are you?", or "sorry, can't talk now".
That is part two, adding real teeth to spoofing a legitimate number. Basically on confirmation that a provider allowed such a call to be made on the US PSTN would result in all their numbers being blocked from the US PSTN until they could prove they had fixed the problem.
