... optional external speaker. Can be either wall,ceiling, or desktop mounted. 3.The customer calls the waiter by pressing the ... the call by depressing the button on the table calling unit. Receiver Technical parameters:Size : 200*123*35mm Color : ... Payment: T/T .Western union .Paypal.EscrowWarranty:12 MonthsFAQApplicationsWireless calling system can be used in restaurants, hotels, hospitals, tea house, ...