gta02, 2007.2: calling w/ headset

[arne anka]

i just plugged the headset in to try calling my voice box. while the sound  
is loud enough w/h headset, in the headset it was some low mumbling.
while the box mumbled i tried alsamixer but none of the sliders changed  
anything!

i never really understood alsa and those state-files are not really  
bedtime stories -- but i think regardlessly what the current state states,  
alsamixer should change that, right?
in contrast, while listening to music the alsamixer indeed changes the  
volume on the headset.

do i need to enable somth?