[Asterisk-Users] spandsp, rxfax, TDM400/zaptel, missed frames, any help?

[Rich Adamson]

> > > Sorry in advance if this is a FAQ...
> > >
> > > I've got a working Asterisk setup based on A at H 2.2. I have a TDM400
> > > card with 2 FXS and 2 FXO ports; PSTN connections come in via the TDM
> > > card.
> > >
> > > I haven't been able to get inbound fax with spandsp and rxfax to work.
> > > Occasionally an all-text fax will come in, though it's usually badly
> > > corrupted, but in most cases, it would appear that the call is
> > > terminated without successful transmission of the fax. I get logs that
> > > look what's included below.
> > >
> > > >From reading the list, it looks like this is caused by the TDM card
> > > missing frames. Does that sound correct? If so, is there any relief in
> > > sight?
> >
> > Its been a problem since the card came out a couple of years ago. So, no
> > it does not appear there is any relief in sight.
> 
> Sigh. What a disappointment! Are there any other options for home
> users to receive faxes over the PSTN through *? Is anyone working on
> an alternative to the zaptel driver that might fix this issue?

I'm certainly not the expert on this topic, but I believe the issue has
to do with the pci bus and probably relates to the TigerJet chip used on
the card. Until that's addressed, any analog modem use through the card
will be marginal at best. (Same issue as with the older x100p card.)

One alternative for low volume faxing is to use an external service. I've
found those to be very economical and I receive all faxes in the form of
a pdf file (much better for me in terms of a distributed office environment).
No more costs associated with junk faxes, toner, paper, etc, etc.

Another alternative is to maintain a single pstn analog line for outbound
faxing, E911, and other such services.

All of the above has been discussed many times on the list and should
be available from the archives.