I’m having some problems with faxing and I’d appreciate any help you can offer.
First my basic setup:
TDM400P configured as 1 FXS / 2 FXO (TDM12B).
Two POTS lines in a hunt group on the FXO ports.
3 SIP phones on our local network.
1 Fax machine (Brother MFC-7820N) attached to the FXS port.
I get “poor line condition” errors from my fax machine whenever I attempt to fax over one of the fxo ports - either direction. I also cannot fax using spandsp/rxfax on incomming calls on the fxo ports. The only thing that seems to work is if I fax from the fax machine to spandsp directly over the fxs port.
Fax Machine on FXS port —> rxfax on spandsp extention
These won’t work:
Fax Machine on FXS port —> outbound FXO —> someone else’s fax
Fax Machine on FXS port —> outbound FXO —> inbound FXO —> spandsp
Someone else’s fax —> inbound FXO —> spandsp
Someone else’s fax —> inbound FXO —> Fax machine on FXS port
I’ve set echocancelwhenbridged=no. I’ve even tried totally turning echo cancellation off - even though I don’t want to keep it this way because we need it for regular voice calls.
Fax detection does seem to work in that when our IVR answers the inbound FXO call and hears the beep, it will route to spandsp or the FXS port depending on how I have it configured.
The only problem seems to be that if a fax travels over the FXO port, it corrupts the condition of the line so that the fax machine can’t even train on it. I don’t get garbled faxes, I don’t get any at all.
I’ve also played with rxgain/txgain settings, but nothing seems to help.
Any ideas? Any way to debug this better?
BTW - I’ve tried Asterisk 1.0.9, 1.2.0-beta1 and the current CVS head. all have the same problem.