Call buttons must work with Receivers. Call buttons are the transmitters only, watch receiver or LED display screen pannels are the receivers. Only watch or call buttons not work.Only watch receivers not WORK!!!! Now our wireless calling systems are widely used in fast food restaurant, food court, clinic, church, hospitals, spa & salons and or other queue occasions. They are welcomed and popular. How we use the wireless calling system:First, the calling buttons are pasted or put or on the table, when the guest have any service, he or she the calling buttons, the receiver (LED screen or watch pager) get signal with vibration or sound, showing the table number, then the waiter know which table to be served. Watch pager Feature: 1). wireless technology 2). Fashionable watch design 3). Dot matrix LCD screen 4).Up to 500 channels 5). Call button data pin support for custom 6). Call button words selectable 7). Single or list display mode 8). Accurate time display 9). Vibration/Buzzer prompt 10). Low-power indication watch pager show the call number, call function and call time, is more functional. Power: USB interface Capacity: 500 pcs of pager transmitters Alert Mode: vibration,beep and flach Sensitivity:-110dBm Frequency:433.92MHz Note: Due to different production batches, there may be slight differences in products. Colour:Photo Color Material:ABS Package Contents: 1 x Wireless Watch Receiver Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.