Fun Call Flows Using SHAKEN/STIR Caller ID Attestation Levels

SHAKEN/STIR (Secure Telephone Identity Revisited and Signature-based Handling of Asserted Information Using toKENs) are protocols developed by IETF that aim to verify if a party is allowed to use a certain number. These protocols are used simultaneously as SHAKEN/STIR or STIR/SHAKEN, both meaning the same thing. The protocols have been implemented in carrier networks and can prevent spoofing of caller ID numbers, which was previously difficult but has increased with the popularity of SIP. Twilio's platform allows users to take advantage of SHAKEN/STIR attestation levels for outbound calls, enabling high deliverability of API calls. For inbound calls, Twilio uses a webhook to send the CallToken parameter, which includes the signed attestation information, and can route incoming calls based on the Attestation level using Programmable Voice features such as <Redirect>, <Dial>, <Say>, and <Record>. These features can be used to implement call screening, voicemail, human detection, and more.