Problem with polarity and fax

Hi, I have asterisk 1.6.2 installed on, I have connected a digital frame, also I have a server connected to the asterisk Lync for the company’s corporate service.

The problem began when trying to connect an analog fax, and we did it, connect to the network a PAP2T lynksis up there all right, when we call a fax from outside the company, it sounds like the first sound and cut off, no matter what fax number you call it, is always the same, some research, we find that the problem seems to be changing the polarity on the line, Asterisk detects this change and cut the call. Maybe this is so? is there any way to disable this option of cutting the asterisk call?, need anything else? debug, logs, etc…?

Thank you very much,

Leandro

You need to configure chan_dahdi.conf to match the actual supervision signalling used on the line. My guess is that you actually have polarity reversal answer supervision, but dahdi has only been configured for line reversal disconnect supervision.