Connect this telephone amplifier to your business phone for loud and clear calls that are amplified up to 170 times louder on your handset or headset.Features. Amplifies incoming voices up to 45dB on your handset or headset. Can be used with any headset with an RJ9 plug. Patented technology enables the amplifier to work with virtually all business telephones. Digital Sound Processing technology eliminates virtually all distortion echo effects and unwanted static. Digital Tone Enhancement allows you to boost and enrich the speech frequencies you cant hear well. Automatic Gain Control optimizes the sound level for superior listening comfort. Automatic Volume Control. AC adapter