Skywolf, the key commands etc for VOX are as follows:
F12 allows you to talk to anyone in your country in range (basically if you can see their icon, they are in range.
You do not need to tune this anywhere. It is there by default and set in stone.
To talk on a tuned channel, the T key is the default key to transmit. This will transmit on whatever channel you have tuned.
To tune a channel for vox, hit the slash key / to bring up the radio bar. You will see 5 channels boxes numbered 1, 2, 3, 4 and V.
Channel V is the vox channel you will tune. You may type in that box the channel number you wish to tune to. IE say you are flying a mission and the mission commander says "tune vox to 129".
Type 129 into the channel V, and everytime you press the T key you will transmit on that frequency. Anybody who is tuned to 129 will hear you, and you will hear them.
You will still hear anyone in range however, on the range frequency. Anyone who you hear, you should also see their name appear in the upper right side of your monitor. You can tell if they are on "range" or "tuned" by the colour of their name.
Normally yellow= tuned (in this case 129)
purple= Range.
You may also tune channel V to a specific person. Simply type their handle in to the V box instead of a number.
If I recall correctly freq's 100-199 or reserved for your country and can be tuned to at any time. Normally, 101 is the default freq if i recall corectly.
Hope this helps a bit.
And to echo Flossy's reply, it's a good read. I highly recommend it.
Cheers,
RTR