Plantronics APV-6B Electronic Hook Switch (EHS) cable for Avaya Phones - communicates electronically with the phone, eliminating the need for the HL10 lifter, allowing you to remotely answer and end your calls without having to be at your phone. Use with the Plantronics "CS" Series Wireless headsets (CS50, CS55, CS70N, CS351N, CS361N)

 Important: This cable is NOT compatible with the new CS540, CS510, CS520, you will need the APV-62 or APV-65 EHS cable, depending on which Avaya phone model you have.

This cable works with the following Avaya model phones:

• 2420, 4610, 4610SW, 4620, 4620SW, 4621, 4621SW, 4622, 4622SW, 4625, 4625SW, 4630SW, 5420, 5610, 5620, 5621

Also See Avaya direct connect headset page for reference

note:
Avaya 24XX and 54XX phones require firmware 4.0 and greater
Avaya 46XX and 56XX phones require 1.8 firmware or greater