Intent i = new Intent(Intent.ACTION_MEDIA_BUTTON);
KeyEvent event = new KeyEvent(KeyEvent.ACTION_DOWN,KeyEvent.KEYCODE_HEADSETHOOK);
i.putExtra(Intent.EXTRA_KEY_EVENT, event );
context.sendOrderedBroadcast(i, null);

try {
    Thread.sleep(800);
    Process process = Runtime.getRuntime().exec(new String[]{ "su","-c","input keyevent 5"});
    process.waitFor();

}catch (Exception e) {
    e.printStackTrace();
}

try {
    Thread.sleep(800);
    Process process = Runtime.getRuntime().exec(new String[]{ "su","-c","input keyevent 6"});
    process.waitFor();

}catch (Exception e) {
    e.printStackTrace();
}

Intent buttonDown = new Intent(Intent.ACTION_MEDIA_BUTTON);
buttonDown.putExtra(Intent.EXTRA_KEY_EVENT, new KeyEvent(KeyEvent.ACTION_DOWN,
KeyEvent.KEYCODE_CALL));
context.sendOrderedBroadcast(buttonDown, "android.permission.CALL_PRIVILEGED");

// froyo and beyond trigger on buttonUp instead of buttonDown
Intent buttonUp = new Intent(Intent.ACTION_MEDIA_BUTTON);
buttonUp.putExtra(Intent.EXTRA_KEY_EVENT, new KeyEvent(KeyEvent.ACTION_UP,
KeyEvent.KEYCODE_CALL));
context.sendOrderedBroadcast(buttonUp, "android.permission.CALL_PRIVILEGED");

Log.d(tag, "InSecond Method Ans Call");
    // froyo and beyond trigger on buttonUp instead of buttonDown
    Intent buttonUp = new Intent(Intent.ACTION_MEDIA_BUTTON);
    buttonUp.putExtra(Intent.EXTRA_KEY_EVENT, new KeyEvent(
            KeyEvent.ACTION_UP, KeyEvent.KEYCODE_HEADSETHOOK));
    sendOrderedBroadcast(buttonUp, "android.permission.CALL_PRIVILEGED");

Intent headSetUnPluggedintent = new Intent(Intent.ACTION_HEADSET_PLUG);
    headSetUnPluggedintent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY);
    headSetUnPluggedintent.putExtra("state", 0);
    headSetUnPluggedintent.putExtra("name", "Headset");
    try {
        sendOrderedBroadcast(headSetUnPluggedintent, null);
    } catch (Exception e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

adb shell am start -n com.android.phone/.InCallScreen -a android.intent.action.ANSWER