asterisk users - Sep 2005 - Max concurrent faxes with txfax/spandsp?

Hi,

I tried to use txfax to send several faxes at the
same time.
It seams, that one can't send more than 3 faxes at once,
or one risks to get 50% and more aborted faxes due to
errors.

The CPU usage is below 97%.
I tried with Opteron and IntelP4: same result.

Ok, I know, that faxing via a digital line is complicate,
and I shouldn't complain, but I would like to know, whether
these are typical values or whether one could increase
the max fax number by any means? Maybe force to a slower,
but more error proof modulation?


Regards,
Roger.


P.S.
After faxing approx 100 faxes,
CLI> show channels
shows a lot of channels, which seam to be forgotten, not
hangup faxlines.
Is this a known weakness of txfax?