STIR/SHAKEN
STIR/SHAKEN is a set of standards that lets carriers cryptographically attest that a call is really coming from the number it claims.
It exists because caller ID was never authenticated: for most of the phone network’s life, the number shown to the person answering was simply asserted by whoever placed the call, which is what made large-scale spoofing possible.
Under the framework the originating carrier signs the call with a level of attestation — how confident it is that the caller is entitled to that number — and downstream carriers verify it. It does not stop unwanted calls by itself; it makes the origin of a call checkable, which is what everything else builds on.
Related
- 10DLC — 10DLC is the US registration framework for sending application-to-person messages from ordinary ten-digit local numbers.
- DNC (do not call) — A do-not-call list records people who must not be contacted, and checking it before dialling is a legal requirement in many places.