Avaya Compatible Plantronics CS540 VoIP Wireless Headset Bundle with Electronic Remote Answer|End and Ring alert (EHS) for Avaya Phones: 1600, 9600 IP Phones: 1608, 1616, 9601, 9608, 9610, 9611, 9611G, 9620, 9620C, 9620L, 9621, 9630, 9640, 9640G, 9641, 9650, 9650C, 9670 Bundle of 2 items - Plantronics CS540 Wireless Headset and Avaya compatible ring alert interface cable Compatible Avaya Phones: 1408, 1416, 1608, 1616, 2410, 4630, 5410, 5420, 6416D+M, 6424D+M, 9404, 9406, 9408, 9504, 9508, 9608, 9610, 9611, 9611G, 9620, 9620C, 9620L, 9621, 9630, 9630G, 9640, 9641, 9641G, 9650, 9650C, 9670 Weighing 21 grams makes the CS540 the lightest in the industry