If you want your Grandstream IP phone to not have any lights illuminated when you are not using it, you can take these few small steps in the web configuration page of your phone to make it go black (all LED's off).
This was tested on a GRP2616, but should be applicable for most desktop IP phones.
Backlight Brightness: Active - Default is 100 (max), i bring it down to 65 so it's softer and not so brigvht
Backlight Brightness: Idle - Default is 60. Set this to 0 (off)
Power Saving Timeout - Default is 0 (off) - By setting it to 1 it turns the display off (outside of office hours if you have this setup)
BLF LED Pattern: Set this to either Reserved Red or Green. This is the colours on the side of the BLF Board. Keeps them turn off off most of the time.
Disable VM/MSG Power Light Flash: Turn this off to disable the Voicemail LED on the phone when there is a new voicemail.
And that's it, your phone's LEDs should all be off when not using the phone.