This is very simple. I'll explain one more time. Lol.

STIR attestation is when my carrier can confirm yours.

If it fails, the call is considered "unverified" and therefore blocked.

If my carrier can verify your carrier, my phone will ring. This blocks spoofed calls primarily.

Real people and companies who are not in my contacts but can pass attestation will ring my phone. That means my insurance can still call me even when they use random numbers. That means genuine businesses can call me. That means I can put up a flyer and say my dog is lost please call me if found. And if a real person finds my dog they can call me and my phone will ring and they can tell me they found my dog. Etc.

That's the dream!