What is STIR/SHAKEN?
STIR/SHAKEN is the United States caller-ID authentication framework. STIR is the cryptographic signing standard from the IETF. SHAKEN is the carrier-deployment profile. Together they let receiving carriers verify that a calling number was actually signed by the originating carrier rather than spoofed.
The three attestations
STIR/SHAKEN uses caller-ID attestation on supported telephone routes. A indicates the originating provider verified the caller and their authorization to use the number; B indicates partial verification; C indicates a gateway entry. Availability and handling depend on the route.
What you see
Calls with attestation A are less likely to be labeled "Spam Likely" on the recipient's screen. Calls with attestation C from unknown sources are more likely to be filtered. The labeling decision is made by the terminating carrier and downstream apps; STIR/SHAKEN provides the input signal.
message.com handling
Attestation and caller-ID treatment depend on the carrier, number authorization and route. Do not treat a verified caller-ID signal as proof of the caller’s identity or promise that a call will avoid spam labeling. Review the STIR/SHAKEN concept guide for the supported integration details.
See it working on message.com.
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