[Asterisk-Users] spandsp and app_rxfax (alternative topic:t38modem)

[Rich Adamson]

> I have used an analog trunk (FXO) AND a station (FXS) both on the same card.
> I thought that it might be related to the hardware so I hooked up an old
> Brother Intellifax 9000 on the station port. Both of these attempts had the
> same problem.
> 
> It is my speculation that the 'cutoff' problem was related to some type of
> 'line noise' and that others successfully using the spandsp code _might_ be
> using T1/E1 rather than analog lines (1FL) but when I started testing using
> an old Fax machine plugged into a station port with a six foot RJ11 on
> either end, I realized that this setup really shouldn't be introducing much
> noise (if any) so I am lost. It happens approximately half way through EVERY
> fax I attempt regardless of sending machine (I tried Dialogic and some
> modems) or port (FXO or FXS) so I just gave up on it.

I believe Steve U. has repeatedly commented on the need to have a very
stable pstn interface, no missed interrupts, no frame sleeps, etc, etc.
To me that translates into resolving well-discussed issues with the
tdm04b card, etc.

So, not likely you running into line noise, but rather missed interrupts,etc.
(I have had the same proble with the spandsp here.)