Inbound fax failures after time change

I have a production system where we have a couple inbound fax lines that perform fax-to-email conversion. Yesterday, inbound faxes from one of the two lines stopped working. Both inbound lines are set to detect fax, and go to the same fax recipient which converts the fax to pdf and delivers to an external email (gmail account shared by a team).

The only change that occurred was the system time sprang forward 1 hour (my guess is daylight savings mis-configured).

Running FreePBX 2.11.0

Registered FAX Technology Modules:

Type : Spandsp
Description : Spandsp FAX Driver
Capabilities : SEND RECEIVE T.38 G.711

1 registered modules

FAX For Asterisk Settings:
ECM: Enabled
Status Events: Off
Minimum Bit Rate: 9600
Maximum Bit Rate: 9600
Modem Modulations Allowed: V17,V27,V29

FAX For Asterisk Components:
Spandsp FAX Driver: 20090502 044449

I’ve done some looking at the log files and running DEBUG on fax. Output is at for anyone interested.

The most interesting item I see is:
[2014-06-02 15:34:01] NOTICE[28903]: chan_sip.c:7921 sip_read: FAX CNG detected but no fax extension

That message has since gone away, but no change in behavior.

FAX Statistics:

Current Sessions : 0
Reserved Sessions : 0
Transmit Attempts : 0
Receive Attempts : 116
Completed FAXes : 0
Failed FAXes : 116

Spandsp G.711
Success : 0
Switched to T.38 : 0
Call Dropped : 3
No FAX : 0
Negotiation Failed : 0
Train Failure : 0
Retries Exceeded : 0
Protocol Error : 0
TX Protocol Error : 0
RX Protocol Error : 0
File Error : 0
Memory Error : 0
Unknown Error : 0

Spandsp T.38
Success : 0
Call Dropped : 2
No FAX : 0
Negotiation Failed : 0
Train Failure : 0
Retries Exceeded : 111
Protocol Error : 0
TX Protocol Error : 0
RX Protocol Error : 0
File Error : 0
Memory Error : 0
Unknown Error : 0

I believe I have some sort of an authentication issue, but I have not tracked down where. I apologize if this rambles. I’m relatively new to all this and I did not build this system; I just get to support it.

OK; found part of the problem. So the faxes get converted to PDF then emailed using postfix which then relays through an IIS 6 server at the site to our hosted exchange (O365). So many ways to break this thing.

Anyway, the relay email account had an expired password. Updated that and updated SMTP settings in IIS. Tested email from the pbx and it queued and sent successfully.

So I know the fax is received and the server is converting it into a .tif. I’m now looking at the conversion from tif to pdf to see if that is where things are breaking.

Fax over VoIP is tenuous at best it seems. If anyone has experienced a similar issue, your insight on a direction to take would be fantastic. Not answers, just direction. Thanks!


My personal solution is to burn all the fax machines and let natural selection take care of the employees that can’t use the scan to email function on the copier.

My 87 year old mother is able to scan and email be a document, I mean come on it’s 2014 why is FAX a relevant technology.

The hours I have spent and you think you got t.38 working then it stops for no reason. Of course it always stops working when the most visible exec in an important client tries to use it.

If someone insists on FAX I just bury the cost of POTS lines into the deal. Makes me sleep better at night.

Hahaha, all too true. That basically describes the boat i’m in now. Sadly, we don’t have a scanner at this office (you would think so with 50+ employees, but no). I won’t go into the backwards, debilitating habits of the powers that are however.

Any experience with the Fax Pro commercial module? $150 looks like a cheap date to me if it will resolve this thing.

Never mind on Fax Pro. It gives me nothing we are not already using. Like Wil-E Coyote, back to the drawing board.

New log file at

Looks like something is breaking with spandsp; will try to rebuild/repair that if I can.