STIR/SHAKEN stands for Secure Telephone Identity Revisited (STIR) and Signature-based Handling of Asserted Information Using toKENs (SHAKEN). This framework ensures the legitimacy of voice calls in the US by assigning each call an attestation – a kind of digital "stamp of approval" from the originating service provider. The attestation confirms that the call originated from the provider's network and is then verified by the receiving provider.
There are three levels of call attestations:
- Full attestation (A) — The service provider has verified its relationship with the caller and confirmed that the caller is authorized to use the displayed phone number.
- Partial attestation (B) — The service provider has verified its relationship with the caller but cannot confirm if the caller is authorized to use the displayed phone number. Currently, Plivo provides 'B' attestation for calls when the US caller ID is verified in our system. You can verify your numbers using the Verified Caller ID API or console.
- Gateway attestation (C) — The service provider confirms that the call was placed on its network but has no direct relationship with the caller (e.g., a call from an international gateway).