Designed for people with moderate to profound hearing loss. Volume control up to 30 times (30 dB), for loud and clear telephone calls. Tone Selector for adjusting sound clarity and distinguishing similar sounding words like "chair" and "share". Exclusive Frequency Screening Tones help you identify the sound frequency that needs amplification. Audio output jack for direct connection to assistive listening devices. Handset is compatible with hearing aid T-coil. Adjustable super loud ringer and bright visual ring flasher. Easy-to-see oversized keypad buttons. Selectable outgoing voice amplification (15 dB) so callers can hear you better. Redial, hold and flash buttons.