STIR/SHAKEN

STIR/SHAKEN is a framework that carriers use to verify caller ID. The names stand for Secure Telephone Identity Revisited (STIR) and Signature-based Handling of Asserted information using toKENs (SHAKEN), but the idea is simple: when a call is placed, the originating carrier digitally signs it to vouch that the calling number is real and authorized. Carriers along the way can check that signature before the call reaches the person you are calling.

The whole point is to fight caller id spoofing, where bad actors fake the number that shows up. By signing calls, carriers make it harder to lie about who is calling. For a legitimate call center, this matters because the signature your carrier applies affects whether your calls go through clean or get flagged.

Why your attestation level matters

The signature comes with a call attestation level that says how confident the carrier is that you own the number. The highest level means the carrier knows you and your cid is genuinely yours. A lower level signals doubt, and calls with weak attestation are more likely to show up as a spam likely label on the recipient's phone. To get strong attestation, your carrier needs to confirm you actually control the numbers you dial from.

For a VICIdial operator, the practical takeaway is to work with a carrier that gives your calls full attestation and to use ani numbers you legitimately own. Borrowed or rotated numbers you cannot prove ownership of will earn weaker signatures and get flagged more often. Getting this right is now part of keeping your answer rates healthy, not just a compliance checkbox.