The plantronics savi office app 50 electronic hookswitch cable for polycom communicates electronically with the phone eliminating the need for a hl10 lifter enables one touch remote callanswer with plantronics savi office wireless headset systems see wwwplantronicscom for full compatibility listings connects to rj45 port of savi office charging base opposite end connect to the phone once connected the ehs cable will send a ringer alert signal to the headset anytime the phone rings an