The button need to be paired with the receiver then the unit can work.</li> Wireless call button/Transmitter work with CallToU Receiver (B078M4BCSV,B078LN663K,B078M3VZ7Q,B078M4Q2Y2,B07BLQM7YJ,B07BLVDG3H,B07BNC7M71,B07BTDTCRH)</li> Smart wireless nurse call button allows a patient or an elderly to press a button requesting assistance</li> Wireless transmitters configure with wireless pager for restaurant,coffee shop,hospital service alert </li> </ul> <b>Produktbeschreibung</b> Features Battery:23A 12V Alkaline battery included Operating Range:500+Feet in open area Waterproof Frequency Range:433MHZ Frequency deiation:0.5MHZ Specifications:2.36*2.36*0.8(60*60*20mm) Low battery indication) </ul> Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement. Sold by-YJL official store