> This page is part of the [Customer.io documentation](https://docs.customer.io). For the complete index, see [llms.txt](https://docs.customer.io/llms.txt).
> Last updated: October 23, 2026
> To take actions in Customer.io from an agent, use the [Customer.io CLI](https://docs.customer.io/ai/cli/get-started.md) or the [MCP server](https://docs.customer.io/ai/mcp/get-started.md).

# Migrate to Firebase Installation IDs

If you send push notifications through FCM, register Firebase Installation IDs (FIDs) with Customer.io instead of FCM registration tokens. FID mode is optional, and your existing token-based integration keeps working until you choose to migrate.

If you send push notifications through FCM, Firebase can register devices with [Firebase Installation IDs (FIDs) ↗](https://firebase.google.com/docs/cloud-messaging/manage-tokens) instead of FCM registration tokens. Starting in version 3.12.0 of `customerio-expo-plugin`, you can turn on FID registration with a plugin option, and the Customer.io SDK registers the FID. Until you do, the SDK keeps registering FCM tokens.

When someone opens a version of your app with FID registration turned on, the SDK replaces the device’s FCM token with the FID on their profile. You don’t need to change anything in Customer.io. To learn how FIDs differ from FCM tokens and how Customer.io sends to each, see [Device IDs](https://docs.customer.io/messaging/channels/push/developer-guide/#device-ids).

## Turn on FID mode

1.  Update `customerio-expo-plugin` to 3.12.0 or later and `customerio-reactnative` to 6.14.0 or later. Use `firebase-messaging` 25.1.2 or later on Android and `FirebaseMessaging` 12.19.0 or later on iOS. On iOS, React Native Firebase 27 uses Firebase iOS 13, which `CioFirebaseWrapper` doesn’t support.
2.  Add the `firebaseInstallationId` option at the top level of your plugin config in `app.json` or `app.config.js`. The plugin turns on Firebase’s FID setting on Android, and on iOS when you use the `fcm` provider.

    ```
    {
      "plugins": [
        [
          "customerio-expo-plugin",
          {
            "ios": { "pushNotification": { "provider": "fcm" } },
            "firebaseInstallationId": {
              "enabled": true
            }
          }
        ]
      ]
    }
    ```

3.  Run `npx expo prebuild`.
4.  If your app calls `CustomerIO.registerDeviceToken()`, pass the FID instead of a token from another package. You can get it with `getId()` from React Native Firebase’s Installations module. Firebase doesn’t return an FCM token in FID mode. On a fresh iOS install, if you set `ios.pushNotification.autoFetchDeviceToken` to `false` and turned off FCM auto-initialization (`FirebaseMessagingAutoInitEnabled`), neither the SDK nor Firebase registers the FID with FCM. Call `Messaging.messaging().register(completion:)` in native code before you read the FID.

To go back to FCM tokens, set `enabled` to `false` and run `npx expo prebuild` again.