Full Duplex Compatibility - both sides can talk naturally
  without clipped words and missed sentences.
Echoes cancellation withautomatic gain control -
 no annoying echo to disturb your important conversations.
Super-sensitive hypercadioid microphones- provides 360
  degree full room coverage for meeting participants to
  speak normally.
Powerful loudspeaker - allows meeting participants to
  carry on the meeting as it is everyone is in the same
  room.
Integrated Keypad - with built-in redial, memory, mute
  and flash functions.

Specifications

Network interface : 2-wire RJ - 11 analog PBX or PSTN
Power Consumption : 12VDC/ 500mA
Audio Bandwidth : 200 Hz to 3500 Hz
Loudspeaker Volume :
  Adjustable up to 89dB peak volume.
Loudspeaker impedance : 8 ohm
Loudspeaker output power : 3W
Microphone Sensitivity : -56dB +/- 3dB
Operating Environment : Temp. : 5 ºC to 40 ºC
  Humidity : 20% - 80% non condensing
Recommended room conditions :
  Reverberation time : <0.4 seconds
  Noise Level : <48 dBA
Dimensions : 310 mm X 310 mm X 60 mm
Weight : 760g