--- source_url: https://www.pubnub.com/docs/faq/integrations title: Integrations FAQ updated_at: 2026-10-27T09:13:26.000Z --- # Integrations FAQ > For AI agents: documentation index at https://www.pubnub.com/llms-full.txt Short answers to common questions about [mobile push notifications](https://www.pubnub.com/docs/integrations/mobile-push-notifications/overview.md). ## Which push notification services does PubNub support? PubNub [mobile push notifications](https://www.pubnub.com/docs/integrations/mobile-push-notifications/overview.md) support Apple Push Notification service (APNs) for iOS devices and Firebase Cloud Messaging (FCM) for Android devices. PubNub forwards a published message to APNs, FCM, or both, depending on whether its payload has a `pn_apns` key, a `pn_fcm` key, or both. For how the forwarding works, see [Mobile push notifications](https://www.pubnub.com/docs/integrations/mobile-push-notifications/overview.md#the-delivery-model). ## Which SDKs support mobile push notifications? Every SDK that can publish, and the REST API, can send a push notification, because a push notification is an ordinary publish with a `pn_apns` or `pn_fcm` key. Registering a device token on a channel needs the Mobile Push API. An SDK supports it if its API reference has a Mobile Push page. If yours doesn't, register devices through the [REST API](https://www.pubnub.com/docs/sdks/rest-api.md). For the full list of SDKs, see [Available SDKs](https://www.pubnub.com/docs/getting-started/available-sdks.md). ## How do I register a device for push notifications on a channel? Register the device token on the channel with the Mobile Push API of your SDK, after you enable [Mobile Push Notifications](https://www.pubnub.com/docs/integrations/mobile-push-notifications/overview.md) and add your Apple Push Notification service (APNs) or Firebase Cloud Messaging (FCM) credentials to the keyset. A registration pairs one device token with one channel, so a publish to that channel can become a push to that device. If you use [Access Manager (v2/v3)](https://www.pubnub.com/docs/security/access-control/overview.md), the client needs `read` permission on the channel. Register the same token on each channel the device should receive push for, because channel groups aren't a valid registration target. For the steps and code, see [Register the device token on a channel](https://www.pubnub.com/docs/integrations/mobile-push-notifications/send-push-notifications-ios.md#register-the-device-token-on-a-channel) for iOS and [Register the token on a PubNub channel](https://www.pubnub.com/docs/integrations/mobile-push-notifications/send-push-notifications-android.md#register-the-token-on-a-pubnub-channel) for Android. To confirm which channels a token is registered on, see [Check push device registration](https://www.pubnub.com/docs/integrations/mobile-push-notifications/check-push-device-registration.md). ## How many channels can I register for push per device and per REST call? Mobile Push Notifications has no limit on the number of channels you register per device or per registration call. The whole registration request must fit within the same size limit as [publish](https://www.pubnub.com/docs/architecture/limits.md#publish). For all push limits, see [API limits](https://www.pubnub.com/docs/architecture/limits.md#mobile-push). ## When does PubNub send a message and when a push notification? A publish always reaches the channel's subscribers as a message. It also becomes a push notification only when its payload has a `pn_apns` or `pn_fcm` key and the channel has devices registered for push. When the keys are present, subscribers still receive the whole message, including those keys, and only the content of `pn_apns` goes to APNs and the content of `pn_fcm` goes to FCM. A [signal](https://www.pubnub.com/docs/pub-sub/publish/send-different-message-types.md#send-a-signal-instead-of-a-message) never triggers a push, even if its payload has a push key. A device that is both subscribed and registered can receive the same publish twice, once as a message and once as a push. For the details, see [What triggers a push and what doesn't](https://www.pubnub.com/docs/integrations/mobile-push-notifications/overview.md#what-triggers-a-push-and-what-doesnt). ## Are push notifications stored in message history? Yes, if [Message Persistence](https://www.pubnub.com/docs/data-storage/message-history/overview.md) is enabled on the keyset. A push notification is an ordinary publish with a push payload, so PubNub stores it like any other message. Message Persistence must be enabled on the keyset before you store or read history, and new keysets don't enable it by default. ## Can I push to sandbox and production with the same keyset? Yes, for APNs. Each device registration and each `pn_push` target in the payload names an APNs environment: * `development` for builds installed by Xcode. * `production` for TestFlight and App Store builds. Keysets are usually split by environment anyway, so a key compromised or misconfigured in one environment can't reach another. For how to map keysets to environments, see [Protecting your keys](https://www.pubnub.com/docs/architecture/authentication/overview.md#protecting-your-keys). ## What does a valid APNs payload look like? A valid APNs payload is a `pn_apns` object that holds an `aps` object and a `pn_push` array. The `aps` object holds the notification, such as the alert text. The `pn_push` array names the push type and the APNs topic and environment to target. The whole payload must fit within the [mobile push limits](https://www.pubnub.com/docs/architecture/limits.md#mobile-push). For a complete example, see [Publish a message with a push payload](https://www.pubnub.com/docs/integrations/mobile-push-notifications/send-push-notifications-ios.md#publish-a-message-with-a-push-payload). ## Why am I not receiving push notifications? A publish can succeed even when the push through Apple Push Notification service (APNs) or Firebase Cloud Messaging (FCM) fails, so check the push setup. The most common causes are: * Mobile Push Notifications isn't enabled on the keyset, or the keys in your app belong to a different keyset, for example the shared `demo` keys. * The APNs or FCM credentials on the keyset are wrong. The FCM private key must come from the same Firebase project as your app. * The device token isn't registered on the channel you publish to, or the token changed after you registered it. * The payload has no `pn_apns` or `pn_fcm` key, or the payload is invalid. * The APNs environment doesn't match the build. Use `development` for builds installed by Xcode and `production` for TestFlight and App Store builds. * The app is in the foreground, or notifications are turned off for the app on the device. To see the errors APNs and FCM return to PubNub, subscribe to the channel's `-pndebug` companion channel. See [Debug push notification messages](https://www.pubnub.com/docs/integrations/mobile-push-notifications/debug-push-notification-messages.md). To find out whether the problem is in your provider setup or in PubNub, see [Test mobile push notifications externally](https://www.pubnub.com/docs/integrations/mobile-push-notifications/test-mobile-push-notifications-externally.md). For platform-specific checks, see the troubleshooting sections for [iOS](https://www.pubnub.com/docs/integrations/mobile-push-notifications/send-push-notifications-ios.md#troubleshooting) and [Android](https://www.pubnub.com/docs/integrations/mobile-push-notifications/send-push-notifications-android.md#troubleshooting). ## Can I send large messages through APNs? No. For APNs, the push payload is limited to 4,096 bytes, or 5,120 bytes for VoIP notifications, counted on the whole APNs payload. PubNub checks this limit before sending. A larger payload can't go through Apple Push Notification service (APNs) as a push. For how the push limits compare with the publish limits, see [API limits](https://www.pubnub.com/docs/architecture/limits.md#mobile-push). ## Which APNs push types can I use? Set `push_type` in the `pn_push` array to the APNs push type that matches your `aps` payload, such as `alert` for a notification the user sees, `background` for a silent update, or `voip` for an incoming call. For every push type Apple defines and when to use it, see Apple's [Sending notification requests to APNs](https://developer.apple.com/documentation/usernotifications/sending-notification-requests-to-apns). For where `push_type` goes in the payload, see [Publish a message with a push payload](https://www.pubnub.com/docs/integrations/mobile-push-notifications/send-push-notifications-ios.md#publish-a-message-with-a-push-payload). ## How do I stop the sender from getting a push for their own message? Add the sender's device token to the exclusion list in the push payload of each message you publish, and PubNub skips that device. * APNs: put the token in `excluded_devices` in the `pn_push` target. * FCM: put it in `pn_exceptions` inside `pn_fcm`. You can list more than one token, for example to skip all of the sender's devices. For examples, see [Exclude the sender's device](https://www.pubnub.com/docs/integrations/mobile-push-notifications/send-push-notifications-ios.md#exclude-the-senders-device) for iOS and [Publish a message with an FCM push payload](https://www.pubnub.com/docs/integrations/mobile-push-notifications/send-push-notifications-android.md#publish-a-message-with-an-fcm-push-payload) for Android. To skip the sender's own messages in real time, see [Exclude your own published messages](https://www.pubnub.com/docs/pub-sub/subscribe/filter-received-messages.md#exclude-your-own-published-messages). ## How do I keep an iOS device registered when its token changes? Apple can invalidate a device token, for example after you change your app's APNs setup. Check the token on every cold start of the app. In `didRegisterForRemoteNotificationsWithDeviceToken`, compare the token APNs returns with the one you saved: * If it changed, remove the old token from PubNub, register the new token on your channels, and save it. * If it didn't change, the device is still registered and you don't need to do anything. For the registration calls, see [Receive the device token](https://www.pubnub.com/docs/integrations/mobile-push-notifications/send-push-notifications-ios.md#receive-the-device-token) and [Register the device token on a channel](https://www.pubnub.com/docs/integrations/mobile-push-notifications/send-push-notifications-ios.md#register-the-device-token-on-a-channel). Last updated at: 2026-10-27T09:13:26.000Z