Glossary Compliance
What is STIR/SHAKEN?
Also called stir shaken, call authentication, attestation, caller id spoofing
STIR/SHAKEN is a pair of standards that let carriers cryptographically sign outbound calls, so the receiving network can verify that the displayed caller ID has not been forged. It exists because caller ID was designed with no authentication at all, which made spoofing trivial and underpinned most illegal robocalling.
The three attestation levels
A signing carrier asserts one of three levels. Full attestation means the carrier knows the customer and confirms they have the right to use that number. Partial means the carrier knows the customer but cannot vouch for the number. Gateway means the call entered the network from elsewhere and the carrier can vouch for neither. Higher attestation makes a call less likely to be flagged downstream.
What it does and does not fix
STIR/SHAKEN answers "is this caller ID genuine", not "is this call wanted". A perfectly signed call from a real number can still be an unwanted sales call, and networks apply separate analytics for that. It also only works where both ends are IP; calls traversing older equipment can lose their signature en route.
What to do if your calls are being flagged
Start by confirming what attestation your outbound calls actually carry, since a number you have the right to use should be getting full attestation and anything less is worth asking your carrier about. Then register the number with the free analytics portals the major mobile networks operate, which is a separate system from attestation and is where most "Spam Likely" labels are decided. Finally, look at calling behaviour: short-duration, high-volume outbound from a single number is the pattern those systems are built to catch.