[Asterisk-Users] Asterisk - fax - spandsp

[Les Caroto]

Hi Steve

 

We have been struggling for some time to get spandsp working properly on our
asterisk system.

We are using a TE410P card with a single E1 from our PTT (Zaptel primary
clock source) and another E1 to a NEC PBX. 

The NEC PBX in turn has an E1 connection to a Tenovis I55 PBX, which then
has Basic Rate connections to a Cycos MRS Fax server.

We never experience problems with the Cycos Fax server (which uses an Eicon
Diva card).

We also do not experience problems on the 7 or 8 fax machines connected to
our NEC and Tenovis PBXs (nor do we hear any 'clicks' on voice calls).

Therefore we conclude that we do not have any 'timing slips' or suchlike
with our setup.

 

However, receiving faxes on the Asterisk with spandsp presents us with a
problem - if we send a fax from a particular fax machine (old MITA machine),
spandsp invariably does not receive the whole fax, cutting it at some
unpredictable point. This particular fax machine is in daily use and works
fine to any other fax machine.

 

My knowledge of fax principles being quite limited, it seems to me that
spandsp communicates perfectly with the transmitting fax machine up to a
point, whereupon it fails to react to the transmitting machine's
instructions to advance to the next line scanned. This results in subsequent
lines being superimposed upon each other, producing a dark horizontal line
somewhere within the page (usually less than halfway).

 

I'm inclined to believe that this must be a small problem which can be
catered for in spandsp's code, and make myself available to send you test
faxes if you would like to verify this problem. 

 

Best regards

 

Les Caroto

Logitel Telecom

Johannesburg

South Africa

 

 


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