How to programmatically answer/end a call in Andro

Question

I am writing an android app in which I need to answer an incoming call, do some work and then end the call. After all the Googling I could find two different ways to achieve this both of which do not work with recent versions of Android, specifically after 4.1, Jelly Bean.

I.) Access "com.android.internal.telephony.ITelephony" using Java Reflection in the Broadcast receiver for "android.intent.action.PHONE_STATE". Below sample code can be found in hundreds of related post:

public class PhoneCallReceiver extends BroadcastReceiver {
 Context context = null;
 private static final String TAG = "Phone call";
 private ITelephony telephonyService;

@Override
 public void onReceive(Context context, Intent intent) {
  if (!intent.getAction().equals("android.intent.action.PHONE_STATE")) 
    return;

  Log.v(TAG, "Receving....");
  TelephonyManager telephony = (TelephonyManager) 
  context.getSystemService(Context.TELEPHONY_SERVICE);  
  try {
      Log.v(TAG, "Get getTeleService...");
      Class c = Class.forName(telephony.getClass().getName());
      Method m = c.getDeclaredMethod("getITelephony");
      m.setAccessible(true);
      telephonyService = (ITelephony) m.invoke(telephony);
      telephonyService.silenceRinger();
      Log.v(TAG, "Answering Call now...");
      telephonyService.answerRingingCall();
      Log.v(TAG, "Call answered...");
      //telephonyService.endCall();
  } catch (Exception e) {
   e.printStackTrace();
   Log.e(TAG,
           "FATAL ERROR: could not connect to telephony subsystem");
   Log.e(TAG, "Exception object: " + e);
  }
 }
}

The problem with this code is that

<uses-permission android:name="android.permission.MODIFY_PHONE_STATE" /> 

is required for this method to work, and this permission has been defined as "for system apps only" from android v 2.3. In short, normal user apps can not define this permission in the manifest file anymore.

II.) Another way is to simulate pushing of the Headset hook which makes Android answer the call. This is done by broadcasting the "Intent.ACTION_MEDIA_BUTTON" as shown in below code.

public class PhoneCallReceiver extends BroadcastReceiver {
 Context context = null;
 private static final String TAG = "Phone call";

 @Override
 public void onReceive(Context context, Intent intent) {
     if (!intent.getAction().equals("android.intent.action.PHONE_STATE")) 
         return;

     String state = intent.getStringExtra(TelephonyManager.EXTRA_STATE);
     if (state.equals(TelephonyManager.EXTRA_STATE_RINGING)) {
         String number = intent.getStringExtra(TelephonyManager.EXTRA_INCOMING_NUMBER);

         Intent answer = new Intent(Intent.ACTION_MEDIA_BUTTON);
         answer.putExtra(Intent.EXTRA_KEY_EVENT, new KeyEvent(KeyEvent.ACTION_UP, KeyEvent.KEYCODE_HEADSETHOOK));
         context.sendOrderedBroadcast(answer, null);
         Log.d(TAG, "Answered incoming call from: " + number);
     }   
     return;
 } 
}

This method works till Android 4.1 after which android has restricted user apps from broadcasting "Intent.ACTION_MEDIA_BUTTON".

So my conclusion is that currently there is no way how we can achieve this in Android 4.1 or later.

Has anybody else found any other solution or workaround to this problem?

Answer 1

As a conclusion to this thread, here is the code that works for me for Android 4.2.2.

--> Call is answered by simulating push of headset hook and keeping the broadcast in try-catch as mentioned by @PravinDodia in abouve thread. (Observe that an exception is thrown and handled in catch and the call is answered anyway. So I guess we can just ignore this exception and continue living life as if nothing happened! )

--> Call is disconnected using ITelephony.

public class PhoneCallReceiver extends BroadcastReceiver {
 Context context = null;
 private static final String TAG = "Phone call";

 @Override
 public void onReceive(Context context, Intent intent) {
     if (!intent.getAction().equals("android.intent.action.PHONE_STATE")) 
         return;
     else {
         String state = intent.getStringExtra(TelephonyManager.EXTRA_STATE);

         if (state.equals(TelephonyManager.EXTRA_STATE_RINGING)) {
             answerPhoneHeadsethook(context, intent);
             return;
         }
         else if(state.equals(TelephonyManager.EXTRA_STATE_OFFHOOK)){
             Log.d(TAG, "CALL ANSWERED NOW!!");
             try {
                    synchronized(this) {
                        Log.d(TAG, "Waiting for 10 sec ");
                        this.wait(10000);
                    }
                }
                catch(Exception e) {
                    Log.d(TAG, "Exception while waiting !!");
                    e.printStackTrace();
                }
             disconnectPhoneItelephony(context);
             return;
         }
         else {
             Log.d(TAG, "ALL DONE ...... !!");
         }
     }  
 }

 public void answerPhoneHeadsethook(Context context, Intent intent) {
     String state = intent.getStringExtra(TelephonyManager.EXTRA_STATE);
     if (state.equals(TelephonyManager.EXTRA_STATE_RINGING)) {
         String number = intent.getStringExtra(TelephonyManager.EXTRA_INCOMING_NUMBER);
         Log.d(TAG, "Incoming call from: " + number);
         Intent buttonUp = new Intent(Intent.ACTION_MEDIA_BUTTON);             
         buttonUp.putExtra(Intent.EXTRA_KEY_EVENT, new KeyEvent(KeyEvent.ACTION_UP, KeyEvent.KEYCODE_HEADSETHOOK));
         try {
             context.sendOrderedBroadcast(buttonUp, "android.permission.CALL_PRIVILEGED");
             Log.d(TAG, "ACTION_MEDIA_BUTTON broadcasted...");
         }
         catch (Exception e) {
             Log.d(TAG, "Catch block of ACTION_MEDIA_BUTTON broadcast !");
         }

         Intent headSetUnPluggedintent = new Intent(Intent.ACTION_HEADSET_PLUG);
         headSetUnPluggedintent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY);
         headSetUnPluggedintent.putExtra("state", 1); // 0 = unplugged  1 = Headset with microphone 2 = Headset without microphone
         headSetUnPluggedintent.putExtra("name", "Headset");
         // TODO: Should we require a permission?
         try {
             context.sendOrderedBroadcast(headSetUnPluggedintent, null);
             Log.d(TAG, "ACTION_HEADSET_PLUG broadcasted ...");
         }
         catch (Exception e) {
                // TODO Auto-generated catch block
                //e.printStackTrace();
                Log.d(TAG, "Catch block of ACTION_HEADSET_PLUG broadcast");
                Log.d(TAG, "Call Answered From Catch Block !!");
         }
         Log.d(TAG, "Answered incoming call from: " + number);  
    }
    Log.d(TAG, "Call Answered using headsethook");
 }

 public static void disconnectPhoneItelephony(Context context) {
     ITelephony telephonyService;
     Log.v(TAG, "Now disconnecting using ITelephony....");
      TelephonyManager telephony = (TelephonyManager) 
      context.getSystemService(Context.TELEPHONY_SERVICE);  
      try {
          Log.v(TAG, "Get getTeleService...");
          Class c = Class.forName(telephony.getClass().getName());
          Method m = c.getDeclaredMethod("getITelephony");
          m.setAccessible(true);
          telephonyService = (ITelephony) m.invoke(telephony);
          //telephonyService.silenceRinger();
          Log.v(TAG, "Disconnecting Call now...");
          //telephonyService.answerRingingCall();
          //telephonyService.endcall();
          Log.v(TAG, "Call disconnected...");
          telephonyService.endCall();
      } catch (Exception e) {
       e.printStackTrace();
       Log.e(TAG,
               "FATAL ERROR: could not connect to telephony subsystem");
       Log.e(TAG, "Exception object: " + e);
      }
 }
}

At least the disconnect functionality works and we know how it works. So those who want to develop a Call Barring application can go ahead. For those like me who want to answer a call, I guess we can use this for now and only hope that it does not stop working in the next version.