in my IPPBX I've implemented an email2fax gateway for outgoing faxes. Once it worked pretty good but meanwhile I cannot send any fax.
About my configuration:
It is a system with Core2Duo processor on a Gigabyte mainboard with 3 telepohony cards. A B100P, a B200P and an A800P.
The B100P is connected to the provider, while the B200P card connects to other local telephony hardware. I use the analog A800P card for the connection to a cable provider via POTS lines, but it is not involved in faxing.
I use Asterisk version 1.8.18, res_fax and the Free Fax For Asterisk module provided by digium.
The fax is received by postfix, passed over to a script which creates a call file and a tiff and passes it to asterisk which then connects over a span belonging to the B100P card. After a while I get errors, either a training error, a 3rd_frm_error, tone errors or no appropiate response from the remote side at all. I've recorded a session, listened to it and I could here unusual clicks from time to time. So this seems all to be related to a poor conection...
Then upgraded from openvox_dahdi 2.6.1 to 2.7.0, because I had the hope to get it up and running again with the newer driver. But, I had no luck.
I cannot remember which driver I used when it worked, but it was probably put together by myself - e.g. not a openvox complete package.
Back then I had no echo cancellation (oslec) on the B100P (HFC-S) card compiled into the driver, but turning it off did not resolve the issue.
The mysterious thing is that I have no problem with phone calls at all. They are very clear...
Since I'm stuck at the moment I ask you guys for an advice about what I can do to further investigate and resolve this issue. In different forums I've read about timing issues beeing a cause of this. Is spandsp involved with oslec? Since I've seen it in the source tree with version 0.0.3. I read about other systems where spandsp let faxes fail, so might this be something I've to investigate?
After the update of the driver I get a notification about /sys/bus/astribanks/drivers/xppdrv/sync missing.
I attached some descriptive files about the system including dahdi_scan and dahdi_test results. If there is something important missing or you need a debug run of a fax call I will provide them on request.
Thank you so far.