VoIP glossary
What is STIR/SHAKEN?
STIR/SHAKEN is the caller ID authentication framework used in the United States and Canada, in which the originating carrier digitally signs each call to confirm the caller is entitled to use the number shown.
STIR/SHAKEN explained
The originating provider adds an Identity header with a signed token and an attestation level. "A" means the provider knows the customer and the number; "B" means it knows the customer but not the number; "C" means it is only passing the call along. Terminating carriers use this to flag or block suspicious calls.
For a business, the practical point is to present only numbers you own or are authorised to use. Calls with full attestation are less likely to be labelled "Spam likely" on the recipient’s phone.
Example
A US company sends calls from its own DID. Its provider signs them with A-level attestation, and they display normally on the recipient’s phone.
Put it into practice
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