scope:

The Signature-based Handling of Asserted information using toKENs (SHAKEN) framework enables a SHAKEN-authorized Voice over Internet Protocol (VoIP) Service Provider to deliver cryptographic proof to a called user, via SIP signaling, that the calling user is authorized to use the calling telephone number. This specification extends the SHAKEN framework to enable conveyance of verified "shaken" attestation levels over Time Division Multiplexing (TDM) interconnects.

ATIS-1000097, Technical Report on Alternatives for Caller Authentication for Non-IP Traffic [Ref 101], which evaluates the viability of implementing this call authentication mechanism for TDM networks, should be considered along with this specification.

Purpose

The current SHAKEN framework provides a set of tools that enable verification of the calling party's authorization to use a calling telephone number for a call. It assumes that the SIP Identity header can be carried end-to-end between Originating Service Providers (OSPs) and Terminating Service Providers (TSPs). Currently this is not always possible due to the use of TDM-based signaling at various stages of the signaling path.

The mechanisms described in this document address this problem by carrying verified "shaken" attestation levels over TDM signaling.