STIR/SHAKEN

STIR/SHAKEN is a set of technical standards that lets phone carriers digitally sign and verify the caller ID on calls that travel over IP networks.

STIR stands for Secure Telephone Identity Revisited. SHAKEN stands for Signature-based Handling of Asserted information using toKENs. Together they let the carrier that starts a call attach a signed certificate saying how well it knows the caller and whether the caller has the right to use the number shown. The carrier on the receiving end checks that signature.

In the United States, the TRACED Act of 2019 directed the FCC to require voice providers to put STIR/SHAKEN in place on their IP networks. The FCC set a June 30, 2021 deadline for most large providers, with extensions for some smaller ones.

Each signed call carries an attestation level:

• A (full): the provider knows the customer and confirms they may use the number.
• B (partial): the provider knows the customer but cannot confirm the number.
• C (gateway): the provider is passing the call along and cannot vouch for it.

For a business that makes outbound calls, the practical point is that your phone provider issues the attestation, not you. To get A attestation, your provider needs to verify your business and confirm you own or are authorized to use the numbers you call from. STIR/SHAKEN does not by itself decide whether a call gets a spam label, but it is one signal carriers and analytics companies use.

Sources

• FCC, Combating Spoofed Robocalls with Caller ID Authentication: https://www.fcc.gov/call-authentication (accessed October 17, 2026)

This entry is general information, not legal advice.