Large 1″ backlit talking keys are easy to see & hear; 1-touch customer service quick dial; Extra-loud amplification with TrueSound(TM) up to 55db of extra clear sound; Calibrated, easy-to-adjust volume & tone control–settings stay in place; Amplified speakerphone up to +15dB; 95dB loud ringer & built-in strobe ring signaler; 3-level speech output control adjusts outgoing voice volume up to 12dB; 9 one-touch memory dial buttons–2 emergency, 6 standard & 1 for customer service; Redial, flash & mute buttons; 2.5mm & 3.5mm audio input for headset, neck loop, T-hook silhouette or patch cord; Built-in strobe ring signaler; 3.5mm vibrating ring alert input for use with optional Bed Shaker (not included); Uses line power & included AC power; Desk or wall-mount; T-coil hearing aid compatible; Includes 4 AAA rechargeable batteries for LCD display;