Plantronics APP-5 EHS has been discontinued. If you have one of the older, discontinued Plantronics wireless headsets such as CS55, CS50, CS70N, CS351N, CS361N, you will unfortunately not be able to use the newer EHS cords. Your options would be to get the older model HL10 handset lifter with right angle plug (60961-34), or buy yourself a brand new wireless headset like the CS540
with the new EHS APP-51
For Polycom Unified IP Phone models 320*, 330*, 321*, 331*, 335, 430, 450, 550, 560, 650, 670 and VVX300, VVX310, VVX400, VVX410, VVX500, VVX600, VVX1500 you may use this APP-5 electronic hookswitch adapter (EHS) instead of the HL10 handset lifter for remote call answer/end capability. The APP5 EHS must be used with Plantronics wireless office headset systems CS50, CS55, CS70VT, CS70N, CS351N, CS361N. The Polycom Unified IP phone models listed above support this electronic hookswitch so no HL10 handset lifter is needed. This device will provide a beep tone in your earpiece to alert you to a new call coming in. Simply press the button on your earpiece from anywhere within your 300 ft. range to answer/end your call.
*IMPORTANT: *For Polycom IP 320, 321, 330 and 331 you will also need Plantronics part # 78333-01 to make this hookswitch adapter work. Please see below.