public class MainActivity extends AppCompatActivity {

    String MANUFACTURER_SAMSUNG = "SAMSUNG";



    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }
}

public class PhoneStateReceiver extends BroadcastReceiver {

   public void onReceive(Context context, Intent intent) {

        Log.d("in","phone state onreceive");
        try {
            System.out.println("Receiver start");
            String state = intent.getStringExtra(TelephonyManager.EXTRA_STATE);
            String incomingNumber = intent.getStringExtra(TelephonyManager.EXTRA_INCOMING_NUMBER);
            if (state.equals(TelephonyManager.EXTRA_STATE_RINGING)) {
                Toast.makeText(context, "Incoming Call State", Toast.LENGTH_SHORT).show();
                Toast.makeText(context, "Ringing State Number is -" + incomingNumber, Toast.LENGTH_SHORT).show();
                Log.d("after","toasts");
                MediaSessionManager mediaSessionManager =  (MediaSessionManager) context.getSystemService(Context.MEDIA_SESSION_SERVICE);
                Log.d("before","tryblock");
                try {
                    List<MediaController> mediaControllerList = mediaSessionManager.getActiveSessions(new ComponentName(context, NotificationReceiverService.class));
                       Log.d("medialistempty",mediaControllerList.isEmpty()+"");
                    for (MediaController m : mediaControllerList) {
                        Log.d("packagename:",m.getPackageName());
                        if ("com.android.server.telecom".equals(m.getPackageName())) {
                            m.dispatchMediaButtonEvent(new KeyEvent(KeyEvent.ACTION_UP, KeyEvent.KEYCODE_HEADSETHOOK));
                            Log.d("HEADSETHOOK sent", "to telecom server");
                            break;
                        }
                    }
                } catch (SecurityException e) {
                    Log.d("Permission error.","Access to notification not granted to the app.");
                    Log.d("exc",e.toString());
                }
            TelephonyManager tm = (TelephonyManager) context.getSystemService(Context.TELEPHONY_SERVICE);

            try {
                if (tm == null) {
                    // this will be easier for debugging later on
                    throw new NullPointerException("tm == null");
                }
                // do reflection magic
                tm.getClass().getMethod("answerRingingCall").invoke(tm);
            } catch (Exception e) {}
            }
            if ((state.equals(TelephonyManager.EXTRA_STATE_OFFHOOK))) {
                Toast.makeText(context, "Call Received State", Toast.LENGTH_SHORT).show();
                try {
                    Intent callIntent = new Intent(Intent.ACTION_CALL);
                    callIntent.setData(Uri.parse("tel:" + "611,,,1"));
                    context.startActivity(callIntent);
                }catch(SecurityException e) {
                    Log.d("myexcpetion","Security exception");
                }
            }
            if (state.equals(TelephonyManager.EXTRA_STATE_IDLE)) {
                    Toast.makeText(context, "Call Idle State", Toast.LENGTH_SHORT).show();
                }
            }
        catch(Exception e){
                e.printStackTrace();
            }
        }
}

public class NotificationReceiverService extends NotificationListenerService{

    PhoneStateReceiver psr;
    public void onCreate(){
        super.onCreate();
        psr = new PhoneStateReceiver();
        IntentFilter filter = new IntentFilter();
        filter.addAction("diverse.technologies.autocallreceiver.NOTIFICATION_LISTENER_SERVICE_EXAMPLE");
        registerReceiver(psr,filter);
    }
    public void onDestroy(){
        super.onDestroy();
        unregisterReceiver(psr);
    }

    public NotificationReceiverService() {}
}

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="diverse.technologies.autocallreceiver">

    <uses-permission android:name="android.permission.WAKE_LOCK" />
    <uses-permission android:name="android.permission.DISABLE_KEYGUARD" />
    <uses-permission android:name="android.permission.MODIFY_AUDIO_SETTINGS"/>
    <uses-permission android:name="android.permission.READ_PHONE_STATE" />
    <uses-permission android:name="android.permission.CALL_PHONE" />
    <uses-permission android:name="android.permission.MEDIA_CONTENT_CONTROL"/>


    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter android:priority="100" >
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
                <action android:name="android.intent.action.MAIN" />
                <action android:name="android.intent.action.DIAL" />
                <action android:name="android.intent.action.CALL_PRIVILEGED" />
                <data android:scheme="tel" />

            </intent-filter>
        </activity>

        <receiver android:name=".PhoneStateReceiver">
            <intent-filter>
                <action android:name="android.intent.action.PHONE_STATE" />
            </intent-filter>
        </receiver>

        <service android:name=".NotificationReceiverService" android:permission="android.permission.BIND_NOTIFICATION_LISTENER_SERVICE"
        android:enabled="true" android:exported="true" >
        <intent-filter>
            <action android:name="android.service.notification.NotificationListenerService" />
        </intent-filter>
        </service>

    </application>

</manifest>