SHAKEN/STIR, an initiative to authenticate calls in the telephony network, aims to verify the authenticity of calls and reduce unwanted robocalls. This technology uses JSON Web Tokens (JWT) and certificates to authenticate callers and determine if they are authorized to use the number they're using to place the call. A new trust-anchor, Secure Telephony Identity Policy Administrator (STI-PA), is introduced to select certificate authorities and provide Service Provider Code tokens for service providers to acquire private keys for signing calls and public keys for verifying calls. The technology uses a standardized SIP header with an identity field containing a Base64 encoded JWT that includes payload information related to the origination and termination numbers, as well as a cryptographic signature. SHAKEN/STIR is expected to roll out in 2020 starting with mobile operators, allowing users to verify their ownership of phone numbers and reducing the volume of unwanted robocalls. The initiative has garnered support from industry organizations and regulatory bodies, including the FCC and US Telecom.