It does not work because it is trivial to fake the source number. A popular form of spam pretends to call from a phone number very similar to yours (they use t

It does not work because it is trivial to fake the source number. A popular form of spam pretends to call from a phone number very similar to yours (they use the same leading 6 digits) to make it look like a neighbor is calling. Hopefully the STIR/SHAKEN implementation will widen and this will be put to bed.