STIR/SHAKEN Explained

STIR/SHAKEN is an industry framework designed to combat caller ID spoofing. Here's how it works and what it means for you.

What the Acronyms Mean

STIR stands for Secure Telephone Identity Revisited, a set of technical standards. SHAKEN stands for Signature-based Handling of Asserted information using toKENs, the framework for implementing STIR across phone networks. Together, they create a system for digitally signing and verifying caller ID information.

How It Works

When you make a call, your carrier digitally signs the call with a certificate verifying that you are authorized to use the phone number displayed on caller ID. The receiving carrier checks this signature. If the signature is valid, the call gets a high "attestation" level. If the carrier can't verify the caller's right to use the number, the call receives a lower attestation or is flagged.

The Three Attestation Levels

Full (A): The carrier has verified that the caller is authorized to use the number. This is the most trustworthy level. Partial (B): The carrier has verified the caller but not their right to use the specific number. Gateway (C): The carrier can't verify the call origin — typically for calls entering the US from international gateways.

Limitations

STIR/SHAKEN verifies that the originating carrier is legitimate, not that the caller has good intentions. A scammer using a properly registered VoIP number can pass STIR/SHAKEN verification. The technology reduces spoofing of numbers the caller doesn't own, but doesn't eliminate all scam calls.