[Asterisk-Users] Asterisk mangling faxes

[michiel betel]

michiel betel wrote:

> Hi list,
>
> Faxes come in over an E1 line  (on an TE410P) here and then are sent 
> to an analog fax machine attached to a T1 (also on the TE410P) & 
> channelbank (CAC1).
> Problem is that almost all faxes we send out and receive are 
> mangled... either only halve pages or very stretched text etc.
> Setup in extensions.conf is just:
>
> exten => ${NN_FAX},1,Answer
> exten => ${NN_FAX},2,Dial(Zap/49,80)
> exten => ${NN_FAX},3,Hangup
>
> echocancel is off for Zap/49 since the path is TDM only....
>
> Any pointers to where to look??
>
> Thanks, Michiel
>
>
We have done some more investigation as to where the actual signal 
degradation took place. Thus we connected out fax machine to an external 
(not Asterisk) Analog line. Faxing directly to this line worked 
perfectly, thus making sure the fault was not in the fax machine. We 
then setup a rule in asterisk to:
    exten => ${NN_FAX},1,Answer
    exten => ${NN_FAX},2,Dial(${TRUNK}/12345678,80) ;(where 12345678 is 
the number of the analog line)
Thus immediately redirecting all traffic on this number to dial out over 
another E1 channel (on the same trunk)  to the analog line.
All faxes directed to NN_FAX now became mangled.

Now for the weird part: The ${NN_FAX} came into the 3rd port of the 
TE410P, the 2nd one is connected to the CAC channel bank, the first port 
was originally connected to another E1, but now disconnected, showing 
RED alarm and its channels commented out in zaptel.conf. This setup 
worked fine for voice... When we reconfigured the Zap setup, having the 
active E1 coming in to the first E410P port (also changing the sync to 
sync on that port) our fax-mangling problems disappeared.

Question now is, is my 4 port E1/T1 card faulty or did I run into a 
Zaptel driver problem which only happens if you don't use the first port 
of the TE410?

Michiel