The Ameriphone SR200B Telephone Ringer, by Clarity®, is ideal for use in the home, the office or while traveling so you will never miss a call. Features Super loud telephone ringer (95+ decibels) Visual ring indicator Adjustable ring volume Adjustable ring tone control (250-1200Hz) Choice of four distinct ring patterns Dual modular phone jacks for easy connection to a standard analog telephone Battery back-up to ensure continued use during a power outage