The caller ID authentication framework that lets voice providers digitally sign the calling number on IP calls so downstream networks can verify it was not spoofed.
STIR/SHAKEN is two pieces of work that fit together. STIR is a set of IETF standards (including RFC 8224 for the SIP Identity header and RFC 8225 for the PASSporT token) that define how a calling number can be cryptographically signed. SHAKEN is the industry profile, developed by ATIS and the SIP Forum, that turns those standards into a practical deployment model for North American carriers, including certificate governance and attestation levels.
In practice, the originating provider's authentication service builds a signed token describing the call, attaches it to the SIP INVITE, and sends the call on. The terminating provider's verification service fetches the signer's certificate, checks the signature and the certificate chain, and passes the result to call analytics, blocking, and display logic. Intermediate providers are expected to carry the Identity header through unchanged.
The TRACED Act of 2019 directed the FCC to require STIR/SHAKEN in the IP portions of provider networks. Large voice service providers had to implement it by June 30, 2021, and smaller providers received extensions that have since run out. Providers with non-IP networks must take reasonable steps toward a non-IP caller ID authentication solution, and every provider must describe its approach in the Robocall Mitigation Database.
Why it matters to carriers
For an originating or intermediate provider, STIR/SHAKEN is no longer optional: unsigned or poorly attested traffic is more likely to be labeled, throttled, or blocked downstream, and gaps in implementation can show up in enforcement actions and RMD reviews. Getting signing, certificate management, and attestation logic right directly affects completion rates for your customers and your standing with the FCC and peer carriers.