the main thing is that it doesn't show in the display what mode it's in on 2 of the three phones. That is the customers main concern, the button is on 3 phones ,when this happens x-100's button still works,shows in display, I can't remember if the other 2 can still toogle day/naight when this happens(they can't see it on there phone so they think it's not working).this happened on our in house system before the new software came out but that fixed it, I will have to check the software level on this on,it was purchased well after the new software was released.