public void onStartCallButtonPressed(StartCallButtonPressedEvent event) {
startCallButtonEventSource.fire(new StartCallButtonEvent());
}
});
event.getEndCallButtonHandler().addEndCallButtonHandler(new EndCallButtonPressedHandler() {
@Override
public void onEndCallButtonPressed(EndCallButtonPressedEvent event) {
endCallButtonEventSource.fire(new EndCallButtonEvent());
}
});