Funny you mention searching because I just did "call volume" and found nothing but a bunch of useless reg tweaks.
It gets rather annoying when someone says search, and yet another person says to search also. We have fingers. Click ctrl+c and ctrl+v instead of making everyone look less intelligent.
And it seems after going from thread to thread, forum to forum i finally found this.
http://pdaphonehome.com/forums/ppc-6...tml#post647390
It is unclear whether it works for the built in speaker vs. a BT headset.