asterisk users - Dec 2003 - modem data calls through FXS / FXO digium cards failing

Hi guys,

I think I posted on this issue before, but didn't get a response.  I've 
still not been able to resolve the issue.

I've got a small installation of Asterisk running one 4 port FXS Digium 
card and 1 FXO Digium card.  I'm having difficulty routing modem call 
through one of the extensions out through the FXO card.  By difficulty, 
I mean it won't work.  The calls won't even sync up.  If I disconnect 
the phone line from the FXO card and run the modem directly through that 
(completely bypassing Asterisk), the calls go through fine as usual.

Is there some sort of line quality I can specify for certain extensions 
to allow data calls to better pass through?  Any options I can specify 
on the Dial application that boost the quality or drop echo cancelling 
or are these strategies even going to do me any good?

Does anyone have a similar hardware configuration working?

Thanks.

jl