[Freeswitch-users] rxgain/txgain dahdi

Ok, I'm googled out! Can anyone point me to some docs on how to set the rx and tx gain for an FXO or FXS channel using dahdi and mod_openzap? I think it goes into /etc/dahdi/system.conf, but can't find any docs on how or where. My /etc/dahdi/system.conf looks like this: loadzone=us defaultzone=us fxsks=1 fxsks=2 fxsks=3 fxsks=4 fxsks=5 fxsks=6 fxoks=7 fxoks=8 Thanks! -Troy