Data or fax comms on native bridge

I realize the VOIP protocol is not condusive to fax or modem connections and even T.38 is shakey.

I am also understanding that timing issues on digium cards prevent faxing from say a PRI card to a TDM400 FXS as there is no clock source referencing.

however my Idea is to be able to fax between an FXS port and an FXO port on the SAME TDM400 card… say port 4 is a POTS line to the PSTN, and port 1 is an FXS station. I dial out from the station to the POTS line, doesnt the TDM400 create a native bridge that should theoretically carry fax/ data communications?

in my case I get crappy results regardless of my echo canceller settings… is this just something i should give up on and figure that direct POTS lines must be used for any fax purposes (I know there are LOTS of articles on faxing over IP but this is faxing via TDM just with asterisk acting as the call handler)

There was a thread about plain FAX’ing using PRI in Asterisk Users mailing list recently. I’m under the impression that one must turn off echo cancellation on the interface.

I am unable to find this thread you are talking about. Can you point me in the right direction?