And it does work, despite what people will say. My carrier blocks outbound phone calls from caller IDs of number we don't own. The next step will be to for carriers to start refusing calls that don't pass attestation.
My carrier is GoogleFi, and I still get several phone calls a day with my cellphone's area code as the incoming number. (At least, it makes it easier to ignore those calls. I really wish I could program my phone to automatically reject any calls from that area code if it's not in my phone book.)
