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STIR/SHAKEN

Updated 2026-10-23 · By the SMS Conecta team (SMSConecta Inc.)

Short answer: STIR/SHAKEN is a caller ID authentication framework letting phone carriers digitally sign and then verify the calling number on IP calls, as a defence against spoofed robocalls. US voice providers are required by the FCC to implement it, and Canada runs it too.

STIR covers the IETF standards for signing caller ID, while SHAKEN is the industry framework that puts those standards to work across carrier networks.

How it works

The originating carrier attaches a signed Identity header (a PASSporT token per RFC 8224 and RFC 8225) to the SIP call, along with an attestation level: A for full (the carrier vouches for the customer and number), B for partial, or C for gateway. The terminating carrier checks the signature against the signer's certificate and can factor the result into call labelling or blocking decisions.

STIR/SHAKEN attestation levels

LevelWhat it means
A (full)The carrier can vouch for both the customer and the number
B (partial)Partial attestation
C (gateway)Gateway-level attestation

How it applies to SMS Conecta

STIR/SHAKEN isn't a listed SMS Conecta feature, and SMS Conecta doesn't publish attestation levels for its calls — that part is handled by carriers in the networks a call travels through.

Related terms

  • Caller ID
  • CNAM
  • SIP

Frequently asked questions

What does an attestation level of A signify?

It means the signing carrier confirmed the customer and verified their right to use that calling number.

Does STIR/SHAKEN actually block any calls?

It verifies caller ID itself; carriers may then factor that result, alongside other signals, into labelling or blocking decisions.

Does SMS Conecta supply STIR/SHAKEN attestation?

No, that isn't a listed SMS Conecta feature.

Related pages

Sources