SHAKEN/STIR

SHAKEN (Signature-based Handling of Asserted Information Using toKENs) and STIR (Secure Telephone Identity Revisited) are cryptographic standards that verify the authenticity of caller ID information. When a call arrives, the carrier verifies: 'Is this phone number really calling from where it claims?' If not, the call is marked suspicious or blocked.

Why SHAKEN/STIR matters:

Caller ID spoofing (displaying a false number) is rampant in robocall spam. A scammer might spoof '+1-415-555-0100' to appear local to the victim. SHAKEN/STIR allows carriers to verify: 'Does the caller actually own +1-415-555-0100?' If not, the call is flagged.

For legitimate pay-per-call operators, SHAKEN/STIR is neutral or beneficial. When you display a +1-415 number, SHAKEN/STIR verifies you actually own and are authorized to use that number. This makes your calls less likely to be filtered as spam.

Implementation:

**STIR**: Carriers cryptographically sign the caller ID. The originating carrier (where the call originates) signs: 'This is legitimate'. The terminating carrier (where the call lands) verifies the signature.

**SHAKEN**: More robust version that includes additional attestation layers. Carriers can attest different confidence levels: 'Full' (we own this number), 'Partial' (we believe the customer owns this), 'Gateway' (third-party carrier confirmed this).

For CallMatrix and pay-per-call platforms, SHAKEN/STIR is important for carrier relationships. Carriers are blocking more calls marked as unauthenticated. Legitimate calls with SHAKEN/STIR authentication are less likely to be filtered.

The FCC mandated SHAKEN/STIR implementation by June 2021, and most major US carriers now enforce it. This has reduced spam volume but also occasionally blocks legitimate calls.