I am not sure that your custom GUI will always be on top of the default one, because the system broadcast receiver and your receiver are both trying to display its GUI on top of the screen. We are not sure which one is called first, but one tricky work to make your GUI on top of the screen is when the phone is ringing call your activity after 1-2 second(s) used handler for that.
new Handler().postDelayed(new Runnable() {
@Override
public void run() {
// TODO Auto-generated method stub
Intent intent = new Intent(context, AcceptReject.class);
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
context.startActivity(intent);
}
}, 2000);
I hope it may help you.