asterisk users - Jun 2006 - In-bound faxing working ~1/3 of time.

Hey, all.  I've got inbound faxing going with SpanDSP's RxFax
application.
 And, when it works, it works great.  However, roughly 2/3 of the time, it
fails partway through the fax, and the sending fax machine breaks contact.

I'm running Asterisk 1.2.4, which works fine in al lother particulars. 
I'm not sure of the SpanDSP version, but it's a recent one.

Oh, forgot to mention: I have a range of DIDs pointing to my 23rd B
channel on my T1, which then goes into my Sangoma A104d card; I've got
echo cancellation turned off (to prevent wonkiness in the fax reception;
with it on, the latency screws stuff up).

Any ideas?

Thanks,

-Ken D'Ambrosio