Call Authentication
The FCC-mandated framework that cryptographically signs calling numbers so terminating carriers can verify the caller ID was not spoofed.
STIR (Secure Telephone Identity Revisited) is the set of IETF standards that define how a calling number is signed. SHAKEN (Signature-based Handling of Asserted information using toKENs) is the ATIS/SIP Forum profile that describes how North American carriers deploy STIR across their networks.
In practice the originating provider signs each outbound call with a certificate tied to its OCN, attaching an Identity header that carries a PASSporT token. The terminating provider verifies that signature and can display or suppress a verification indicator to the subscriber.
STIR/SHAKEN proves who put the call on the network and how confident that provider is in the calling number. It does not prove the call is wanted, legal, or truthful — a fraudster with legitimate numbers can still receive full A attestation.
Every US voice provider is required to implement STIR/SHAKEN or file a robocall mitigation program. Signing alone does not stop fraud, which is why the FCC also expects affirmative, effective mitigation measures.
The three confidence levels an originating carrier assigns when signing a call, describing how well it knows the customer and their right to use the calling number.
The SIP header that carries the signed PASSporT token proving a call's caller ID was authenticated by the originating provider.
The signed JSON Web Token inside the Identity header that asserts the calling number, called number, attestation level, and origination identifier.
The central authority that decides which providers are eligible to obtain STIR/SHAKEN signing certificates and issues the tokens needed to request them.
SipShield scores live SIP traffic with patented AI so the controls behind this term run automatically — and leave the audit trail regulators expect.