Super Comfort Phone Headset with Noise Cancelling Microphone Specialized for Avaya phones.
Some Avaya phones models are special which require microphone amplification on headset. This headset comes with circuit box on cable to make sure microphone voice is loud enough for the other end to be heard.
Compatible with below models(including but not limited):
11xx series:

1120e, 1140e, 1150e, 1165e

94xx, 95xx series:

9404, 9406, 9408, 9504, 9508

16xx or 96xx series:
J139, J169, J179, 1608, 1616, 9608, 9610, 9611, 9611G, 9620, 9620C, 9620L, 9621, 9630, 9630G, 9640, 9640G, 9641, 9641G, 9650, 9650G, 9650C, 9670
14xx, 24xx, 46xx, 54xx, 56xx or 64xx series:

1408, 1416, 2410, 2420, 4606, 4610, 4610SW, 4612, 4620, 4620SW, 4621, 4621SW, 4622SW, 4624, 4625SW, 4630, 4630SW, 5410, 5420, 5610, 5620, 5621, 5625, 6416D+M, 6424D+M, QE4610