1. Creating google application

Go to firebase developer console

Sign up or login using your gmail account, create a new project or use an existent one.

2. Go to settings

using the top left corner menu and select project settings

3. get the Sender Id and the APIkey

on “cloud messaging” tab you will find the APIkey and the sender Id

4. Install Push Notification plugin

Now you can go to your Cordova/phone-gap project and install the amazing plugin for sending push notification for both Android and iOS

cordova plugin add phonegap-plugin-push --variable SENDER_ID="XXXXXXX" //DON’T forget to replace the ‘xxxxx’ with your created sender id

in this step you get your TOKEN which will be used in the server side

Now inside your .run function and after device get ready you can use this plugin like

angular.module('starter', ['ionic'])

.run(function($ionicPlatform) {
  $ionicPlatform.ready(function() {
   var push = PushNotification.init({
    android: {
        senderID: "12345679"  // send id from google app
    }
});

push.on('registration', function(data) {
    // data.registrationId   TOKEN is here
});

push.on('notification', function(data) {
    // data.message,
    // data.title,
    // data.count,
    // data.sound,
    // data.image,
    // data.additionalData
});

push.on('error', function(e) {
    // e.message
});
  });
})

you can find more details on how to use the plugin here

5. Testing your app

now you need to simulate your server to send a notification and there are many solutions for that you can simply use this PHP class to this and your server side code may be like :

  $apiKey = "YOUR GOOGLE API SERVER KEY";
  $devices = array('YOUR REGISTERED DEVICE ID');
  $message = "The message to send";

  $gcpm = new GCMPushMessage($apiKey);
  $gcpm->setDevices($devices);
  $response = $gcpm->send($message, array('title' => 'Test title'));

I have made a sample server side live link to use it in testing you can use it simply as :

http://test.w34.co/gcm.php?id=TOKEN HERE&apikey=API KEY HERE