How can I play the default notification sound?

There is any way to play the default system notification sound? I'm trying to do this when the device receives a remote push notification when the app is running. I'am able to play an embedded sound, but not the system notification sound...

var soundObj = MonoTouch.AudioToolbox.SystemSound.FromFile(sound) ??
                                       MonoTouch.AudioToolbox.SystemSound.FromFile("defaultAlert.caf");
if (soundObj != null)
{
  soundObj.PlaySystemSound();
}