[CS50 AVAYA 2420, 4600, & 5000 EHS DISCONTINUED] (See image to the right) 1) Disconnect AC/DC power cord from headset charger base. 2) Connect both the RJ9 and 3.5mm (accessory plug) from Plantronics Electronic Hookswitch for Avaya 1400 & 9000 Series Phones / Plantronics Electronic Hookswitch for Avaya 2420, 4600, & 5000 Series Phones into Plantronics base. 3) Connect RJ9 into headset jack on Avaya phone base. 4) Reconnect AC/DC power cord to headset charger base. 5) Set compat dial to 1 on headset charger base. 6) Test the headset! Plantronics Electronic Hookswitch for Avaya 1400 & 9000 Series Phones Compatible AVAYA Phone Models: 1408 9608 9670 1416 9611 9620L 1608 9620 2410 1616 9621 4630 9404 9630 6416D+M 9406 9640 6424D+M 9504 9641G 9508 9650 Plantronics Electronic Hookswitch for Avaya 2420, 4600, & 5000 Series Phones Compatible AVAYA Phone Models: 2420 5420 4610 5610 4610SW 5620 4620 5621 4620SW 4621SW 4622SW 4625SW