I am thinking of this topology:

caller->freeswitch->proxy

in proxy, there will be some routing module as carrierroute or so and then call is sent back

callee<-freeswitch<-proxy

thing is, if only one call is placed, 4 channels are used. If I used sangoma transcoding card, every channel has to be transcoded to the internal FS coded and back, so 8 transcoding channels in sangoma driver are used for just one call (!). How could I tell freeswitch to do not pass SDP information to the proxy side and let it use only 2 channels as in standard caller->callee call.

Thanks,

Mino