STIR/SHAKEN is a system designed to verify phone numbers and authorization of customers to use them. It has been put in place to combat the growing number of robocalls and caller ID spoofing.
STIR: Secure Telephone Identity Revisited
SHAKEN: Secure Handling of Asserted information using toKENs
STIR/SHAKEN has three levels of 'Attestation':
Full ('A') Attestation - the service provider has authenticated their customer originating the call and they’re authorized to use the calling number.
Partial ('B') Attestation - the service provider has authenticated their customer originating the call but can't verify they’re authorized to use the calling number.
Gateway ('C') Attestation - the service provider has authenticated from where it received the call, but can't authenticate the call source (e.g., International Gateway call).
STIR/SHAKEN and Aircall
As of July 1st, 2021 for the US, STIR/SHAKEN has been activated on all domestic calls in these countries. All calls will meet at least 'B' Attestation, with many meeting 'A' Attestation.
This means that your outbound calls should not be flagged or blocked by other providers due to a lack of compliance with this system.
Some calls may still be flagged as spam by other systems, and for more information on this please visit Why is My Number Displaying as Spam?