Sidetone settings

[cm21]

I've been evaluating the Yealink T48G for deployment and am wondering a few things regarding sidetone settings (hearing yourself, whether in headset or handset mode):

1) I see a post regarding some aspects here:
http://forum.yealink.com/forum/showthread.php?tid=600
But it's not clear to me whether this would affect sidetone of the handset, headset, or both.

With my evaluations, handset sidetone is on the low side, but acceptable. Headset sidetone is non-existent as far as I can perceive. Are there settings available to separately adjust the two?

2) I see the voice.side_tone setting referenced in the above link, but so far have not been able to locate that in any official documentation. Am I missing a document somewhere?

Thanks.