This is the cordless, clarity-enhancing telephone that not only makes voices 50 dB louder by amplifying high-frequency sounds, but also reduces low-frequency noise that causes interference and distortion. Unlike lesser models that only adjust for volume, this phone employs multiband compression, noise reduction, and acoustic echo cancellation to ensure conversations are louder and clearer, whether conducted from the handset or the base station's speakerphone. Its 5.8GHz transmission to either handset (additional handsets sold below) avoids interference from other wireless devices, and it has adjustable volume control and can be set to four different tones for a customized listening experience. A bright visual ringer alerts you to incoming calls, and it has an easy-to-read display with large back-lit buttons. It has a built-in digital answering machine that allows you to play back messages at your preferred speed. In addition to call waiting and caller ID, the telephone can store up to 40 names and numbers. Handset's rechargeable battery provides up to four hours of talk time. Not for use by those with cardiac pacemakers. Base plugs into AC (battery backup requires four AA batteries). Base: 7 3/4" L x 4 1/2" W x 9 1/4" D. (3 1/4 lbs.)