RexaThe short answer
STIR/SHAKEN exists to make caller ID spoofing detectable. The originating carrier signs the call with an attestation level, and the terminating carrier verifies it. For outbound voice AI the practical consequence is that calls with weak attestation are more likely to be labelled as spam or blocked, regardless of how legitimate the campaign is.
In detail
STIR defines the token: the originating carrier attaches a signed identity header asserting the calling number and an attestation level. SHAKEN defines how carriers deploy that in the SS7-and-SIP world, including the certificate authority structure that makes signatures verifiable between competing carriers.
Three attestation levels are defined. Full attestation, or A, means the carrier both authenticated the customer and confirmed they are entitled to use the number. Partial, or B, means the customer is known but the number is not verified as theirs. Gateway, or C, means the call entered the network from a source the carrier cannot vouch for at all. Terminating carriers and analytics vendors treat these very differently.
Attestation is not a spam verdict and does not by itself put a label on a call. It is an input to the analytics engines that do decide, alongside call volume, duration patterns and complaint rates. A legitimate campaign with full attestation can still be flagged if its behavioural profile looks like a robodialer, and improving attestation without changing that profile does not fix the problem.
Related terms
CNAM
CNAM is the caller-name information displayed alongside a calling number on the recipient’s handset.
Carrier
A carrier is a company that operates telephone network infrastructure and terminates or originates calls on it.
A2P 10DLC
A2P 10DLC is the US registration framework under which businesses declare their identity and messaging use case before sending application-to-person traffic from ordinary ten-digit numbers.
DID
A DID is a telephone number assigned to an organisation that routes an inbound call directly to a specific destination without passing through an operator.