Amplifier is designed for use with traditional or new wideband VoIP phone systems. VoIP-ready Vista M22 amplifier is compatible with most office phones. Clearline audio technology enhances speech clarity and helps to reduce repeats, errors, and listening fatigue. Easy to use, with one-button headset/handset selection, plus controls for both incoming and outgoing volume. When used with wideband VoIP system, the Vista M22 delivers enhanced audio and more natural speech, reducing repeats, errors, and listener fatigue. Reduces the level of incoming loud noises, such as fax tones or whistle blasts. Helps reduce echo associated with VoIP telephone technology. Reduces the level of background noise picked up by the headset microphone and reduces the level of noise on the incoming signal to improve call quality. Amplifier uses two AA batteries (included). Includes 10' coiled cable to Quick Disconnect, which lets you walk away from your phone without removing your headset.