... easy-to-use speaker On/Off, Microphone Mute, and Headset buttons. These buttons are lit when active. For added ... amplifier when using a headset. This feature allows the handset to remain in its cradle, making headset use simpler.The convenient ... for easy, decibel-level adjustments for the speakerphone, handset, headset, and ringer. The handset is hearing aid-compatible (HAC). Additional volume ...