Problem with fax and modem

I have Asterisk with Sangoma card ( A104d ).
Asterisk is connected to Ericsson Business Phone 250 ( 2 spans )
and 2 telco’s (PRA).
I have four faxes connected to BP250 ( external lines analog or digital ). There is a problem when users try to send document through fax. The connection is established
with other side ( Asterisk rings through telco and answers ), but when the
document is being sent some errors occur.

It looks that way:

telco <-> Asterisk <-> BP250 <-> Fax

With dialing everything is ok.

When telco is connected to BP250 everything is ok, we can use faxes.
telco <-> BP250 <-> Fax

Can you help me ? Maybe there is something with the cables, but dialing
works fine.

I’ve had problems with fax and the Sangoma A104D. I gave up but some tips are to make sure you have the latest Sangoma firmware and you DISABLE echo cancellation for faxes.

We have the A104D card ourselves, it is a very fiesty card if settings are not correct it can be a pig to work with.

You must have Echo cancellation turned off, both on the card configuration and its own conf files, and also switched on in Asterisk, the echo cancellation plays havoc with the sending of faxes and also receiving them as well, this is a must to do.



Unfortunately it did not help.
I have other Asterisk with enable hardware cancellation
and there faxes and modems work.
Maybe it is a matter of kind of fax or modem ?
Fax or modem connection looks like standard dial for me.
Can I debug it somehow ?

I’m not familiar with the card etc. but what codec is used?

It needs to be G.711 and no negotiation is allowed. Maybe that is left out of the desription since it is obvious :wink:


Patrick Arkley

Problem was connected with timming. My setting for Sangoma was incorrect
( Master/Slave and timming source ). Hardware Echo Cancellation is enabled
and it doesn’t matter for fax and modem.

My setting for Sangoma was incorrect ( Master/Slave and timming
source ).

I have the same problem… can please tell me what exactly you’ve changed to fix the problem.

Jorg B.

I have the same issue. Can you tell me what changes you made?