Serene Innovations HD-60J High Definition Amplified Jumbo-key Phon High-Definition Sound Technology for un-matched clarity, amplifies incoming sound up to 600 times (over 55+dB), the most powerful in its class. The amplifier comes on automatically on every call or on demand. Selectable Digital Speech Tone Enhancement allows you to boost and enhance the speech frequencies that you cant hear well, making difficult to hear words intelligible again. It is more convenient, more accurate and far superior than the traditional tone controls. Latest Digital Sound Processing (DSP) technology eliminates virtually all distortion, echo effects and unwanted squealing commonly found in other ordinary amplified phones. Automatic off-hook audible and visual warnings to alert improper hang-up, preventing accidental blocking of incoming calls. Jumbo and brightly backlit keypad making it the easiest to see among all telephones; 12 one-touch programmable memory buttons; Two (front and side) visual ring flashers; 95+dB super loud ringer with adjustable ringing volume and tone controls. Battery back up (batteries not included) for power outages; 3.5 mm jack for neck-loop, tele-coil and other assistive accessories; Hearing aid compatible handset; One year warranty.