Implement PUSH notifications in Xamarin Android APP with PortSIP PBX 12.x
This guide gives you step-by-step instructions on how to implement the PUSH notifications in the SIPSample project of PortSIP VoIP SDK which can receive VoIP push notifications sent with PortPBX 12.x.

1. VoIP notifications

The official documentation can be found here. Some of the advantages are:
  • The App is automatically relaunched if it’s not running when a VoIP push is received
  • The Device is woken up only when VoIP push occurs (to save battery)
  • VoIP pushes go straight to your app for processing and are delivered without delay
  • The App is automatically relaunched if it’s not running when a VoIP push is received

2. Prerequisite settings

Since PortSIP PBX uses the Google Firebase to send PUSH notifications, we need to configure some settings to get this working.

3. Creating a new App project in Firebase

Add a new project to the Firebase console. You will need to set the project name and country. For example, I will call my project SIPSamplePush.
Select "Add Firebase to your Android app". Set a package name for your app. I only set my package name and omit the SHA-1 because I don't use Firebase for my app's authentication.
Click the REGISTER APP button here to download google-services.json. This is an important file and you will need to put it into your app.
Important: Please note that the Android package name is also referred to as “App ID”. We will use it in future settings.

4. Add the Xamarin Google Play Services Base Package

Since Firebase Cloud Messaging is dependent on Google Play Services, the Xamarin Google Play Services - Base package must be added to the Xamarin.Android project. You will need version 212.0.0.2 or later.
  1. 1.
    In Visual Studio, right-click References > Manage NuGet Packages ...
  2. 2.
    Click the Browse tab and search for Xamarin.GooglePlayServices.Base.
  3. 3.
    Install this package into the Portsip.Android.Test project:
If you get an error during the installation of the NuGet, please close the Portsip.Android.Test the project, open it again, and retry the NuGet installation.
Note: If the problem persists with the error message “Unable to install package: “Xamarin.GooglePlayServices.Base xx.xxxx.x”, it indicates that you are trying to install this package into the target project “MonoAndroid,Version=vx.0”, while the package does not include any assembly references or content files to be compatible to this framework. For more details, please contact the package author. Please start the Visual Studio installer to upgrade to the latest version. Once upgraded, right-click the project, click Properties > Target Framework to choose the latest platform. After this, repeat Step 3.
When you install Xamarin.GooglePlayServices.Base, all of the necessary dependencies are also installed. Edit MainActivity.cs and add the following using statement:
using Android.Gms.Common;
This statement makes the GoogleApiAvailability class in Xamarin.GooglePlayServices.Base available to Portsip.Android.Test code. GoogleApiAvailability is used to check for the presence of Google Play Services.

5. Add the Xamarin Firebase Messaging Package

To receive messages from FCM, the Xamarin Firebase - Messaging package must be added to the app project. Without this package, an Android application cannot receive messages from FCM servers. 1. In Visual Studio, right-click References > Manage NuGet Packages ... 2. Check Include prerelease and search for Xamarin.Firebase.Messaging. 3. Install this package into the Portsip.Android.Test project:
When you install Xamarin.Firebase.Messaging, all of the necessary dependencies are also installed. Next, edit MainActivity.cs and add the following using statements:
using Firebase.Messaging; using Firebase.Iid; using Android.Util;
The first two statements make types in the Xamarin.Firebase.Messaging NuGet package available to PortSip.Android.Test code. Android.Util adds logging functionality that will be used to observe transactions with FMS.

6. Add the Google Services JSON File

The next step is to add the google-services.json file to the root directory of your project:
  1. 1.
    Copy google-services.json to the project folder.
  2. 2.
    Add google-services.json to the app project (click Show All Files in the Solution Explorer, right click google-services.json, then select Include in Project).
  3. 3.
    Select google-services.json in the Solution Explorer window.
  4. 4.
    In the Properties pane, set the Build Action to GoogleServicesJson (if the GoogleServicesJson build action is not shown, save and close the Solution, and reopen it):
When google-services.json is added to the project (and the GoogleServicesJson build action is set), the build process extracts the client ID and API key and then adds these credentials to the merged/generated AndroidManifest.xml that resides at obj/Debug/android/AndroidManifest.xml. This merge process automatically adds any permissions and other FCM elements that are needed for connection to FCM servers.

7. Add services to app

Two services should be added to use Firebase Cloud Messaging service: a basic code for testing if push notification works, and other codes to handle receiving message or sending message in your app according to your design.
Add a service that extends FirebaseMessageService
To be able to receive any notification in your app, you should add a service which extends FirebaseMessageService as below:
using Android.App;
using Android.Content;
using Android.Util;
using Firebase.Messaging;
namespace PortSip.AndroidSample.Test
{
[Service][IntentFilter(new[]
{
"com.google.firebase.MESSAGING_EVENT"
}
)]public class MyFirebaseMessageService : FirebaseMessagingService
{
const string TAG = "MyFirebaseMsgService";
public override void OnNewToken(string p0)
{
base.OnNewToken(p0);
notifyTokenRefresh(p0);
}
public override void OnMessageReceived(RemoteMessage message)
{
string type = p0.Data["msg_type"]string content = p0.Data["msg_content"];
string from = p0.Data["send_from"];
string to = p0.Data["send_to"];
string pushid = p0.Data["x-push-id"];
}
private void notifyTokenRefresh(string token)
{
Intent intent = new Intent(this, typeof(PortSipService));
intent.SetAction(MyService.ACTION_TOKENREFRESH);
intent.PutExtra(MyService.DEVICE_TOKEN, token);
StartService(intent);
}
}
}

8. Test and send your first push notification

To see if the setup works, run a test by sending a test message to your own mobile.
In the Firebase console, write down your message and choose an app. Click "SEND MESSAGE".
Now you should get a PUSH notification on your Android mobile. If your app is running in the background, you will get it on the mobile's notification center; otherwise, you can see it in your Android Monitor log (we have to put a code to log incoming messages) like this.
If the setup is successful, you should get a notification on your mobile. Sometimes, it can take a couple of minutes for the message to send and arrive, so just be patient for a little while.

9. Enable PUSH in App

Adding SIP header "x-p-push” to REGISTER message. We use it to tell PortSIP PBX this client is enabled with PUSH.
namespace PortSip.AndroidSample.Test
{
[Service][IntentFilter(new string[]
{
"PortSip.AndroidSample.Test.PortSipService"
}
)][IntentFilter(new string[]
{
ACTION_TOKENREFRESH
}
)]public class MyService : Service,IPortSIPEvents, IOnCompleteListener
{
public const string ACTION_TOKENREFRESH = "token_refresh";
private string pushToken;
private bool needPush = true;
private PortSipLib mEngine;
private string String appid=”com.portsip.sipsamplepush”;
//you app id
public override void OnCreate()
{
base.OnCreate();
...
//get token
FirebaseInstanceId.Instance.GetInstanceId().AddOnCompleteListener(this);
}
public void OnComplete(Task task)
{
if(task.IsComplete&& task.IsSuccessful)
{
pushToken = task.Result.ToString();
}
}
public override StartCommandResult OnStartCommand(Intent intent, StartCommandFlags flags, int startId)
{
if (intent != null)
{
if(ACTION_TOKENREFRESH.Equals(intent.Action))
{
setPushHeader(needPush);
if (online)
{
mEngine.refreshRegistration(0);
}
}
return StartCommandResult.Sticky;
}
/**
* @param support true enable Push, false disable Push.
*/
private void setPushHeader(bool support)
{
if (!String.IsNullOrEmpty(pushToken))
{
String pushMessage = "device-os=android;device-uid=" + pushToken + ";allow-call-push="+support+";allow-message-push=" + support + ";app-id=" + appid;
mEngine.addSipMessageHeader(-1, "REGISTER", 1, "x-p-push", pushMessage);
}
}
}

10. Possible problems

  • Compilation problems can be related to wrong version numbers in your build.gradle files.
  • If you see a message like "com.google.firebase.crash.FirebaseCrash is not linked. Skipping initialization." in your Android Monitor log, it is ok because we don't use this Firebase Crash Analytics service.

11. Get server key and sender ID

(1). In the Firebase console, click the “Settings” button and choose the “Project settings” menu.
(2). In the “Settings” tab, click the “Cloud Messaging” tab, you will see the “Server key” and “Sender ID”, please note it.

12. PortSIP PBX

Now sign in PortSIP PBX 12.0 Management Console, select menu “Settings” > “Mobile PUSH”. Click the “Add New App” button, you will see below screen:
Please setup the following items:
  1. 1.
    Enabled – check it to enable PUSH and un-check to disable PUSH.
  2. 2.
    Apple and Google both are provided with the production PUSH server and development PUSH server for sending PUSH notifications. The development production server is usually used for your development stage. Once your app is released, you can change this setting to the production server.
  3. 3.
    App ID – the ID that you created in step 3. Note: This ID is case-sensitive.
  4. 4.
    Google Server Key and Google sender ID – the key and ID are what you noted in step 9.2.
Click the “Apply” button and the PUSH service is enabled in PBX.
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On this page
1. VoIP notifications
2. Prerequisite settings
3. Creating a new App project in Firebase
4. Add the Xamarin Google Play Services Base Package
5. Add the Xamarin Firebase Messaging Package
6. Add the Google Services JSON File
7. Add services to app
8. Test and send your first push notification
9. Enable PUSH in App
10. Possible problems
11. Get server key and sender ID
12. PortSIP PBX