---
title: "What is STIR/SHAKEN? | Chargezen"
description: "A set of standards US phone carriers use to sign calls and confirm the caller ID number is real, to fight spoofed robocalls."
url: "https://chargezen.com/glossary/stir-shaken"
lang: "en"
---

Canonical URL: https://chargezen.com/glossary/stir-shaken

# STIR/SHAKEN

STIR/SHAKEN caller ID authentication

Phone

A set of standards US phone carriers use to sign calls and confirm the caller ID number is real, to fight spoofed robocalls.

## What is STIR/SHAKEN?

STIR (Secure Telephone Identity Revisited) and SHAKEN (Signature-based Handling of Asserted information using toKENs) work together. When a call starts, the caller's provider attaches a digital signature saying how sure it is that the caller is allowed to use that number. The receiving carrier checks the signature. **The law behind it.** The TRACED Act of 2019 required voice providers to put caller ID authentication in place, and the FCC set a June 30, 2021 deadline for most providers' internet-based networks. **Attestation levels:** - **A (full):** the provider knows the customer and that they are allowed to use the number. - **B (partial):** the provider knows the customer but can't confirm the number, for example when calls come through a business phone system. - **C (gateway):** the provider only knows where the call entered its network, such as a call from abroad. **What it does and doesn't do:** - It helps carriers and call-blocking apps decide whether to show "spam likely" or block a call. - It confirms the number, not the name. The name a person sees comes from separate caller name (CNAM) databases. - A signed call can still be unwanted. Carriers also look at call patterns and complaints. **For a business,** the practical steps are to place calls through a provider that signs them with the strongest attestation it can, use numbers you're authorized to use, and register your numbers with the free caller registration services the major carriers' analytics companies offer if your calls get mislabeled.

## Example

A store calls a customer back from its own number through its provider, which signs the call with A attestation. The customer's carrier sees a valid signature and shows the number normally instead of "spam likely."

## Why STIR/SHAKEN Matters

It's why some business calls reach customers and others get labeled as spam, so it affects whether people pick up.

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