Can't they just make technology simple?

Having problems with your new headset (perhaps a Plantronics USB Audio 510) with Skype - you can't talk when you're in a call because it's muted and you can't unmute?

Try this:

First:
SKYPE-->Tools-->Options-->Sound Devices-->(untick) Enable Automating Sound Device Adjustment Settings-->Save

Quit SKYPE

In config.xml change:
<Call><AGC>1</AGC>
And
<General><AGC>1</AGC>

so that both are zero.

In shared.xml change the <VoiceEng> bit to:

<VoiceEng>
<AGC>0</AGC>
<MicVolume>127</MicVolume>
<VoiceEng>

255 is max volume and 0 = low. Range is 0 (off) to 255 (maxim)
255 could be much too high, so please reduce if necessary

Save both files and restart Skype. Hope it works!