What is STIR/SHAKEN?

STIR/SHAKEN is a revolutionary technology created to combat caller ID spoofing in telephone calls. These protocols work together to validate the caller's identity and fight fraud in the telecommunications sector.

How does STIR/SHAKEN work?

The two protocols have complementary roles:

• STIR (Secure Telephone Identity Revisited) — Defines the technical standard for telephone identity authentication
• SHAKEN (Signature-based Handling of Asserted information using toKENs) — Establishes how operators implement STIR in their networks

The authentication framework operates in three phases:

1. Authentication

The call origin is validated through a digital certificate that confirms the legitimacy of the displayed number. The originating operator signs the call with its private key.

2. Transmission

The certificate accompanies the call through the networks, allowing each operator along the path to verify authenticity. The token is transmitted in SIP headers in JSON Web Token (JWT) format.

3. Verification

The destination provider confirms the certificate's validity using the originating operator's public key, available in accessible HTTP repositories, ensuring authentic caller identification.

Attestation levels

There are three primary attestation levels that indicate the degree of confidence in caller identification:

Benefits of STIR/SHAKEN

1. Fraud reduction — Significantly reduces fraudulent call schemes and robocalls
2. Consumer trust — Restores consumer confidence in caller identification data
3. Efficient management — Enables efficient identification and management of legitimate calls
4. Regulatory compliance — Preparation for future Anatel regulations

Implementation in Brazil

The Brazilian implementation of STIR/SHAKEN differs from other countries, using a system based on SIP redirection instead of the integrated certificate approach used in the United States. This choice accommodates the heterogeneous legacy networks present in Brazil.

Conclusion

STIR/SHAKEN represents a significant advancement for telecommunications security and reliability, protecting consumers and companies against fraud. With the global expansion of these initiatives, widespread adoption is essential to reduce fraud and increase user confidence in telecommunications infrastructure.