1. Transfer, Mute, Conference Call, Paging, Hold, Check, Remove. 2. STN graphic display module LCD 3. Incoming call indicator 1. Using STN ... ( MUTE ): you can close the microphone ( including a handle and a hands-free microphone )while in conversation state, indicator lights ... volume) can be adjusted quickly by Volume control key.8. Conference key (CONF), you can quickly convened a meeting, which ...