Unwanted calls and illegal robocalls are a frequent source of complaints for telecom regulators in many countries. To address caller ID spoofing and fraudulent calls, regulators in North America and France are deploying STIR/SHAKEN based frameworks, and in France specifically the MAN project (Mécanisme d’Authentification des Numéros).

This article explains what STIR/SHAKEN is, how attestation levels work, how it is used for calls in the United States and Canada, and how caller ID authentication is implemented in France, including information about Aircall number ranges and ARCEP requirements.

What is STIR/SHAKEN?

In simple terms, STIR/SHAKEN is a set of specifications and frameworks for attesting, signing, and verifying caller identity. The goal is to apply digital certificate and security technologies to phone calls, similar to what is used for internet transactions, in order to reduce caller ID spoofing.

  • STIR (Secure Telephony Identity Revisited)

    • An IETF standard

    • Defines a signature to verify the calling number

    • Specifies how this signature is transported in SIP signaling

  • SHAKEN (Signature-based Handling of Asserted information using toKENs)

    • A framework developed by the ATIS/SIP Forum IP-NNI task force

    • Provides a practical implementation profile for STIR that voice service providers can use

STIR/SHAKEN attestation levels, United States and Canada

In the U.S. and Canada, STIR/SHAKEN uses three levels of attestation. These describe how confident the originating service provider is about the identity of the caller and their right to use the number.

  • Full, A attestation
    The service provider has authenticated the customer originating the call and confirmed that they are authorized to use the calling number.

  • Partial, B attestation
    The service provider has authenticated the customer originating the call but cannot verify that they are authorized to use the specific calling number.

  • Gateway, C attestation
    The service provider has authenticated the point from which it received the call, for example an international gateway, but cannot authenticate the original call source.

STIR/SHAKEN and Aircall in the U.S. and Canada

As of July 1, 2021, for the United States, STIR/SHAKEN has been activated on all domestic calls in the U.S. and Canada.

  • All calls meet at least B attestation.

  • Many calls meet A attestation.

This means that Aircall outbound calls should not be flagged or blocked by other providers due to a lack of compliance with this system.

Some calls may still be flagged as spam by other systems. For more information on this, please see Aircall number displaying as spam.

Caller ID authentication and STIR/SHAKEN in France

In France, unwanted calls and illegal automated calls are also clearly identified as an issue.

Two main elements support caller ID authentication:

  • Legislative action by the French Parliament, known as the Naegelen law, which aims to better regulate telemarketing.

  • Rules defined by the national regulator ARCEP (Autorité de régulation des communications électroniques, des postes et de la distribution de la presse).

Together, these have led to the rollout of a mechanism for authenticating calling numbers, known as the MAN project (Mécanisme d’Authentification des Numéros). This mechanism is intended to prevent caller ID spoofing and is an important step in framing telemarketing practices and combating fraud.

Aircall number ranges and ARCEP compliance

Aircall uses its own number ranges, officially assigned by ARCEP.

These numbers:

  • Are not sub-allocated or resold by another operator

  • Are registered directly in the name of Aircall

This allows Aircall to:

  • Ensure complete traceability of the numbers used

  • Maintain full compliance with French regulatory obligations related to fraud prevention and abusive telemarketing

STIR/SHAKEN based implementation in France

In France, caller ID authentication is implemented using a model based on STIR/SHAKEN principles, adapted to the French context.

In the chosen architecture:

  • The originating service provider is responsible for:

    • Attesting to the level of confidence in the caller identity

    • Obtaining a signed certificate associated with the call

    • Transmitting this certificate to transit and terminating service providers

  • The terminating operator is responsible for:

    • Verifying the signed certificate received with the call

    • Using this information when processing the call according to the applicable rules

For more information, you can refer to the technical documentation STIR/SHAKEN – Implementation in France (RBBN).

Regulatory timeline in France

Given the legislative and regulatory measures already in place, French law required the deployment, in July 2023, of an interoperable mechanism for authenticating caller identifiers between operators.

The solution used in France is based on STIR/SHAKEN mechanisms that have been implemented in the United States and Canada, with administrative and operational differences specific to the French environment.

Summary

  • STIR/SHAKEN provides a standardized way to attest, sign, and verify caller identity using digital certificates.

  • In the United States and Canada, Aircall applies STIR/SHAKEN on all domestic calls, with each call receiving at least B attestation and many calls receiving A attestation.

  • In France, caller ID authentication is implemented through the MAN project, which builds on STIR/SHAKEN principles and complies with the Naegelen law and ARCEP rules.

  • Aircall number ranges in France are directly assigned by ARCEP, which supports traceability and compliance in the fight against fraud and abusive telemarketing.