... so everyone can easy to know who is calling.4. Call buttonTechnical Parameter:Working voltage: DC12VWorking current: ≤35mAUse Frequency: ... T/T, Western union, Paypal, EscrowWarranty: 1 year FAQApplicationsWaiter call bell system can be used in restaurants, hotels, hospitals, ... system?1. Wireless receiver, installed on the count 2. Call button, installed on each table3. Signal repeater (optional), ...