Plantronics APV-63 Electronic Hook Switch (EHS) cable for Avaya Phones communicates electronically with the phone.  Compatible with Plantronics Savi and Plantronics CS500 series wireless headsets:

Plantronics CS540, CS510, CS520, Plantronics Legend CS , Plantronics Savi WO100,   Plantronics Savi WO200,   Plantronics Savi WO300  Plantronics Savi WO350 , Plantronics Savi W740,  Plantronics Savi W710 , Plantronics Savi W720 ,  Plantronics Savi W730 ,  Plantronics Savi W745

This EHS cable works with the following Avaya model phones:

• J139, J159, J169, J179, J189, 1608, 1408, 1416, 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

Also See Avaya direct connect headset page for reference

Old Poly part # 38734-11

New HP part # 85R01AA