**We have more of these available. Call for Quantity.Compatible with IP500 digital station, analog station, and VCM base cards * Connects to IP500 base card * - When connected to IP500 base card, it provides 4 loop-start analog trunk ports Also provides DTMF, caller ID (ICLID), busy tone detection * Adjustable echo cancellation - Selectable to Off, 8, 16, 32, 64, and 128 milliseconds * Power Failure Transfer - When fitted to an IP500 analog phone base card. During power failure, the first extension port (port 1) is connected to the first analog trunk (port 9) * Maximum - 4 per IP500 control unit