Smart switch 1:waiting 2:D.N.D 3: Clean Used inside the room. Smart hotel ... /220V,12V/5V.3: It can show:Waiting,D.N.D,Clean.4: Used inside the room.5: Packing ... “Please wait a moment” and doorbell button failure, 2 minutes later, "Please wait," restore a dark backlight ... CertificationThe product is based on the International requirements GB16915.2-2003 to design and production, and its performance ...