android oreo get incoming call number in service

I am implementing code to get incoming call number in android Oreo. For that I am using broadcast receiver in service. Here is the code that I have done so far.

public class CallService extends Service {
private static final int ID_SERVICE = 101;
BroadcastReceiver brSms;

public class MyReceiver extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {
        TelephonyManager telephony = (TelephonyManager)context.getSystemService(Context.TELEPHONY_SERVICE);
        telephony.listen(new PhoneStateListener(){
            @Override
            public void onCallStateChanged(int state, String incomingNumber) {
                super.onCallStateChanged(state, incomingNumber);
                System.out.println("incomingNumber : "+incomingNumber);
                Toast.makeText(context,""+incomingNumber,Toast.LENGTH_LONG).show();
            }
        },PhoneStateListener.LISTEN_CALL_STATE);
    }
}


@Override
public int onStartCommand(Intent intent, int flags, int startId) {
    super.onStartCommand(intent, flags, startId);
    return START_STICKY;
}

@Nullable
@Override
public IBinder onBind(Intent intent) {
    return null;
}

@Override
public void onCreate() {
    super.onCreate();



    IntentFilter filter = new IntentFilter();
    filter.addAction("android.intent.action.PHONE_STATE");
    brSms = new MyReceiver();
    registerReceiver(brSms, filter);




    // Create the Foreground Service
    NotificationManager notificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
    String channelId = Build.VERSION.SDK_INT >= Build.VERSION_CODES.O ? createNotificationChannel(notificationManager) : "";
    NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(this, channelId);
    Notification notification = notificationBuilder.setOngoing(true)
            .setSmallIcon(R.mipmap.ic_launcher)
            .setPriority(PRIORITY_MIN)
            .setCategory(NotificationCompat.CATEGORY_SERVICE)
            .build();

    startForeground(ID_SERVICE, notification);
}

@RequiresApi(Build.VERSION_CODES.O)
private String createNotificationChannel(NotificationManager notificationManager){
    String channelId = "my_service_channelid";
    String channelName = "My Foreground Service";
    NotificationChannel channel = new NotificationChannel(channelId, channelName, NotificationManager.IMPORTANCE_HIGH);
    channel.setImportance(NotificationManager.IMPORTANCE_NONE);
    channel.setLockscreenVisibility(Notification.VISIBILITY_PRIVATE);
    notificationManager.createNotificationChannel(channel);
    return channelId;
}
@Override
public void onDestroy() {
    unregisterReceiver(brSms);

 }
}

The code is not working. I tried various options given in stack overflow. I have added permission for foreground service in my manifest file. How can I get incoming call number even if the app is closed or killed by user?

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