# Alerts for updated cardholder phone numbers

Notify cardholders when their phone number is changed.

You can set up phone number change alerts to notify cardholders when their phone number is updated. Stripe sends the alert to the phone number on file before the change, this way the original cardholder receives it even if a fraudulent attacker made the update.

This feature helps your cardholders detect account takeover attacks early, potentially before any fraudulent activity occurs on their card. Usually during an account takeover, attackers first change a cardholder’s phone number to receive subsequent 3DS authentication messages and fraud challenges instead of to the cardholder.

## Before you begin

- Make sure you’re collecting [phone numbers](https://docs.stripe.com/api/issuing/cardholders/object.md#issuing_cardholder_object-phone_number) for your cardholders
- Cardholder phone number change alerts are only available to cardholders with phone numbers in the following countries. Attempts to send alerts to other phone numbers, or to cardholders who are physically outside of these countries, won’t be delivered.
  - GB
  - US

## How it works

When a cardholder’s phone number changes, Stripe sends an SMS to the previous phone number. The message includes the last four digits of the cardholder’s card, the last four digits of the new phone number, and the name of the Issuing business.

Cardholder phone number change alerts share the same SMS opt-out channel as [fraud challenges](https://docs.stripe.com/issuing/controls/fraud-challenges.md). If a cardholder replies STOP to either type of message, they stop receiving both. Keep this in mind if your integration relies on fraud challenge SMS delivery.

### Cardholder phone number change alerts for Connect platforms

If you use [Connect](https://docs.stripe.com/issuing/connect.md) with Stripe Issuing, the setting applies at the platform level and covers all cardholders across all connected accounts. Connected accounts can’t configure it independently.

## Enable or disable alerts

You can enable cardholder phone number change alerts in the **Settings** > [Issuing](https://dashboard.stripe.com/settings/issuing/fraud-controls) page in the Dashboard.