STIR/SHAKEN
STIR/SHAKEN is the acronym for Secure Telephone Identity Revisited / Signature-based Handling of Asserted information using toKENs.

Secure Telephone Identity Revisited / Signature-based Handling of Asserted information using toKENs
A framework designed to combat caller ID spoofing in telephone networks, especially in the fight against illegal robocalls.
- STIR stands for Secure Telephone Identity Revisited, is a set of technical standards developed by the Internet Engineering Task Force (IETF). It specifies how to digitally sign calls at the start of their journey through the phone network, verifying that the caller ID has not been tampered with.
- SHAKEN stands for Signature-based Handling of Asserted information using toKENs, a set of implementation guidelines created by the Alliance for Telecommunications Industry Solutions (ATIS). SHAKEN defines how STIR’s digital signatures should be used and verified within carrier networks.
In practice, when a call is placed, the originating carrier attaches a cryptographic signature attesting to the legitimacy of the caller ID. Downstream carriers then check this signature. If verified, the call is delivered with an indicator that the caller ID is authenticated. If not, the call may be marked as potentially fraudulent or blocked.
STIR/SHAKEN has become a regulatory requirement in the United States under FCC rules and is being adopted by major telecom providers. The framework improves consumer trust in phone calls by helping to distinguish legitimate calls from spoofed ones, though it does not stop robocalls entirely—especially those originating outside of compliant networks.