1) Plug the cord with the green sticker into the PHONE port in the back of the headset base
2) Plug the cord with the pink sticker into the ACC port in the back of the headset base
3) Plug the other end of the EHS into the HEADSET jack of the phone
4) Set compat to A and move dipswitch #1 down (bottom right in the back of the cube)
Note: If this is their first EHS cord, they will have to enable hookswitch mode in the Web GUI
To use Plantronics EHS headset, go to the GXP2130/GXP2140/GXP2160/GXP2170 web GUI -> Settings -> Preferences -> Headset type. Select "Plantronics EHS" and reboot the phone to take effect.