This six (6) microphone conference phone comes with all you need for clear, full-duplex conversations. Everything you need to sound professional, without the high price tag! It is full-duplex, which allows for simultaneous two way conversations. Clear, natural sound made possible by wide band acoustic echo cancellation, dynamic noise suppression, and phone line echo suppression. It comes with six microphones, four internal and two external. With automatic, intelligent microphone mixing built in they can hear you well too. You can store twenty numbers in the phone book, and speed dial twenty groups The 3 line LCD displays caller ID The 5 Watt speaker generates volume up to 90dB