How are Notifications Pushed to our Mobile Devices?

Most people have a love/hate relationship with mobile push notifications. On the one hand, they keep us updated with the information we willingly asked to be updated on. On the other hand, for people like me, that constant activity on my phone is annoying and distracting. 

My friends tease me, but I can’t go to sleep or do anything, for that matter when I have a little red dot in the top right corner of an app on my iPhone. Once I’ve checked out that notification, only then I can move on. Nevertheless, I need those notifications, so I can’t turn them all off. 

What are push notifications?

A push notification is a message that pops up on a mobile device, such as a sports score, an invitation to a flash sale or a coupon for downloading. App publishers can send them at any time, since users don’t have to be in the app or using their devices to receive them. Push notifications look like SMS text messages and mobile alerts, but they only reach users who have installed your app. All the mobile platforms – iOS, Android – have their own services for supporting push.

Why are push notifications important?

Push notifications are very effective at helping users stay engaged with an app or re-engaging with an app they haven’t opened in a while. This is particularly useful because re-engaged users have significantly higher in-app conversion rates and lower acquisition costs than new users. Because you can receive pushes while you’re browsing in-app or even when your device is locked, this makes them a great way to convey messages of urgency, such as breaking news, current traffic conditions, or limited-time offers.

A Brief History of Push Notifications

Apple and Google are the leaders in the push notifications feature. 

In 2009, Apple launched the first-ever push notification service – Apple Push Notification Service (APNs). Google didn’t stay behind for too long and launched its Cloud to Device Messaging service (C2DM) in 2010. 

Rich notifications with images and calls to action appeared in 2013 on Google’s service, and then Apple added interactive buttons to their service in 2014. 

In October 2014, Google acquired Firebase; it merged with Google’s push notification service and became known as Firebase Cloud Messaging (FCM).

So how does a notification reach your device?

Let’s see how this works with Firebase Cloud Messaging (FCM) which supports both iOS and Android notifications.

An FCM implementation includes two main components for sending and receiving:

  1. A trusted environment such as Cloud Functions for Firebase or an app server on which to build, target, and send messages.
  2. An Apple, Android, or web (JavaScript) client app that receives messages via the corresponding platform-specific transport service.
Source: Firebase

To setup our apps on FCM, we need to upload the relevant Apple and Google certificates. And then integrate the Firebase SDK into our mobile apps. 

What follows is then what happens when users install the app and we give permissions to allow push notifications.

  1. App registers with FCM the Sender ID, API Key and App ID. 
  2. FCM returns a registration token
  3. This registration token is then sent to our backend where it needs to be stored along with the user details. 
  4. When our backend needs to send a notification, it sends the token, message and other details to FCM.
  5. If the client is not online, Firebase stores the messages. It keeps checking regularly to see if the device/client is online to send the notification. 
  6. If the client is online it forwards the message to the relevant transport layer. 
  7. The client/app receives the notification and displays it to the user. 

Here is a lovely infographic I came across on Push Notifications on

2 thoughts on “How are Notifications Pushed to our Mobile Devices?

  1. Hey Kenrick, great read! I particularly enjoyed your in-depth discussion of the history behind push notifications, since it was something I hadn’t really thought of before. Being a fellow tech blogger myself, I also really appreciate how organized and well-formatted everything was – it definitely made the content much more digestible overall. Keep up the awesome work!

    Liked by 1 person

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