provides intelligent amplification to make soft sounds audible, while keeping loud sounds bearable. Digital Clarity Power features: - Multiband Compression - Acoustic Echo Cancellation - Noise Reduction - Increase incoming sounds up to 40 decibels - Three (3) tone settings to customize your listening experience - Call Waiting Caller ID - 2.4 GHz technology for more freedom of movement - Bright visual ringer in both handset and base - Vibrating handset ringer Features: - Digital Clarity Power™ - Caller ID and Call Waiting Caller ID - 50 name and number phone book - Vibrating handset ringer - Battery back-up in the base - One (1) one-touch emergency speed dial key - Adjustable ringer volume - Last number redial - Tone/Pulse setting - Flash, Mute and Page functions - Includes belt clip - 3.5mm neckloop jack - 2.5mm headset jack - 40 channel operation - Hearing Aid Compatible - One (1) Year Limited Warranty C4210 Amplified Telephone Item: 74210.000 Outlets: 3.5mm neckloop jack 2.5mm headset jack Power Requirements: Requires an RJ11 modular phone jack and a standard 120-volt outlet. Battery back-up requires four (4) AAalkaline batteries (not included)