Desktop conference phone automatically adjusts the phone circuit for the country code. Full duplex technology allows participants to speak and listen at the same time. Wide-band, acoustic echo cancellation ensures your calls are clear and crisp. Automatic microphone mixing detects which microphones are being used to maximize the clarity of your calls. Four internal Omni-directional microphones pick up sounds from every angle. 20-number phone book makes calling frequent numbers fast and easy. LCD Caller ID shows you who's calling before you answer the phone. Conference phone also features microphone mute, call hold, redial and flash buttons, volume up/down switches, standard keypad, adjustable ring volume and more.