Wireless calling system widely used in many service area. It is consist of table button for guest and signal receiver for waiter. They can press the button on table/wall when need help, the desk number will show on the receiver with music/sound. So the waiter could offer service very timely. how does wireless call system work (function) Specification of K-2000A display: 1. With high strength high strength ABS shell 2. Desktop or wall mounted 3. Show one group number with 3-digit number. 4. Show different service type by dot (1 dot=Call, 2 dot=Bill, 3 dot=Drink ), or by the last letter(c=call, b=bill, d=drink) 5. It can work with 999pcs call buttons in max 6. It can save 63 calling info in turn, and apply in basic service position. 7. Dimension: 195*135*30mm 8.Color: Black and White Technical parameters Working voltage: DC7.5V