Product description Polycom SoundStation2 Avaya 2490 Conference Phone Expandable Amazon.com Meet all your teleconferencing needs with the full-duplex Polycom SoundStation. This conference phone is ideal for small- to medium-sized rooms containing one to five people. With conventional, half-duplex speakerphones, only one party can speak at a time without clipping off the other party's voice. Echoes and howling can further disrupt your conversations and lead to costly misunderstandings. But because of the SoundStation's full-duplex operation, you can speak naturally and hear both sides of the conversation clearly. The SoundStation ensures high sound quality with three microphones and a digitally tuned speaker for 360-degree coverage of an office or conference room. Polycom's Acoustic Clarity Technology uses digital signal processing with analog telephone lines to eliminate the clipping and fading that plague most speakerphones. This technology improves speaker and microphone performance over the full bandwidth of the telephone line--300 to 3,500 Hz. Other features that boost sound quality include dynamic telephone-line and dynamic room-echo cancellation, signal depression, microphone switching, and digital filtering of voice signals.The SoundStation has a full alphanumeric keypad for dialing, with a mute button and a flash key to access functions like hold, conference, and transfer. There is also a jack to plug in a tape recorder. Dual-colored LEDs signal phone status, and other controls include a ringer volume, speaker volume, and microphone mute.The SoundStation does not work with all analog phone system or with an adapter (sold separately) for digital phone systems. It comes with a wall module, 25-foot power cable, 7-foot telephone cable, and a one-year warranty.