... Mhz Distance is about 100 M We sell cordless calling system for restaurants, coffeeshop, night club, supermarkets, shopping ... different models. One base can fit to 999 Calling set ( if is need)Frequency:315/433 ... 15 " ,if the two hundred and fifty table is calling, the base display " 250 " ,and so on . ... base when first call,if anther table is calling,the display will change to anther table number ...