STIR/SHAKEN
US (FCC — IP networks by 30 Jun 2021); Canada (CRTC 2021-123 — by 30 Nov 2021) · also called call authentication, SHAKEN
A framework that cryptographically signs caller ID so networks can verify a call really came from the number it claims.
STIR/SHAKEN is a suite of standards for authenticating caller ID on IP-based voice networks. The originating provider cryptographically signs an assertion about the calling number ("attestation"); downstream providers verify the signature, giving confidence the number was not spoofed in transit.
US voice providers register their robocall-mitigation efforts and implementation status in the FCC's Robocall Mitigation Database. STIR/SHAKEN authenticates the signature on a call — it does not by itself prove the caller is trustworthy.
A call passing STIR/SHAKEN is not certified "safe." Attestation confirms the signature and number assertion, not the caller's intent — a fully-attested call can still be a scam.