The is a DECT 6.0 PLUS expandable digital answering system with three cordless handsets. This answering system boasts an enhanced noise reduction feature that suppresses background noise around the caller while simultaneously enhancing their voice so its easier to hear especially if theyre calling from a noisy location. A powerful battery back-up system keeps you connected even when the power goes out. Keep a charged handset in the base unit and you can still make and receive calls with the other cordless handsets. To maximize clarity or accommodate hearing loss a Tone Equalizer control feature actually lets you adjust bass mid-range or treble tones in a callers voice for maximum clarity. The DECT 6.0 PLUS takes the superb sound quality and outstanding range of DECT 6.0 phones to a whole new level.