Summary:ASTERISK-19436: outbound fax over t38 gateway can't pass
Reporter:Dmitry Melekhov (slesru)Labels:
Date Opened:2012-02-27 22:09:32.000-0600Date Closed:2012-02-28 07:59:24.000-0600
Versions:10.2.0 Frequency of
Environment:Centos 6.2 x86, asterisk 10.2.0-rc1Attachments:( 0) fail-fax1-fail-t38.pcap
( 1) fail-fax1-from-ast-t38only.pcap
( 2) fail-fax1-incoming-t38.pcap
( 3) fail-fax1-ok-t38.pcap
( 4) fail-fax1-pre20.pcap
( 5) myDebugLog.t38

I don't know which component has problem, so I just guessed.

There is asterisk box, connected to panasonic kx-td500 over PRI link with TE122.

If we try to send fax with following path:

panasonic 500 extension fax machine -> asterisk -> ooh323 -> cisco3845->...-> fax machine

fax can't pass. I'll attach console log with udptl debug.
always reproducable.

If I send fax in path
panasonic 500 extension fax machine -> asterisk (ReceiveFAX) it is received successefully all the time.

If I send fax from asterisk with SendFax as following:

asterisk(SendFax) -> panasonic 500 -> asterisk -> ooh323 -> cisco3845->...-> fax machine
it always passes.

So ooh323 works OK, fax part works OK, t38 works OK, but not with fax machine (we tested to different).

Inbound faxes in reverse direction, i.e.
-> ooh323 -> asterisk -> panasonic -> fax machine
always pass.

Where can be problem? What can I debug to find it?

Thank you!
Comments:By: Dmitry Melekhov (slesru) 2012-02-27 22:10:28.255-0600

console log

By: Dmitry Melekhov (slesru) 2012-02-28 00:58:33.858-0600

I got more info.

As I see from tcpdump asterisk can send faxes on 4800 and fax machines we have can't.
I'll upload dump files.
Question is where is problem... :-(

By: Dmitry Melekhov (slesru) 2012-02-28 00:59:01.738-0600

fax attempt from fax machine

By: Dmitry Melekhov (slesru) 2012-02-28 00:59:34.503-0600

fax from asterisk passed on 4800.

By: Dmitry Melekhov (slesru) 2012-02-28 01:21:24.542-0600

fax directly from asterisk (i.e. sendfax to ooh323), only 7200!

By: Dmitry Melekhov (slesru) 2012-02-28 01:21:44.242-0600

incoming fax, only 7200

By: Dmitry Melekhov (slesru) 2012-02-28 01:23:49.587-0600

OK, looks like problem is in fax speed.
Only 7200 is available...
But if we use addpac gateway connected to panasonic I guess it gets us 9600 on the same link, just because faxes pass....
May be this is spansdp problem?
I use 0.0.6pre18...

By: Dmitry Melekhov (slesru) 2012-02-28 01:55:40.637-0600

looks like 0.0.6pre20 solved problem for one fax machine (at least one fax passed), but not for another - the same problem 9600 and no attempt to drop speed :-(

By: Dmitry Melekhov (slesru) 2012-02-28 01:57:57.947-0600

0.0.6pre20 only 9600

By: Dmitry Melekhov (slesru) 2012-02-28 04:04:18.280-0600

added faxbuffers=>8,full to chan_dahdi.conf , no result.
and no passed faxes from both machines now :-(

By: Matt Jordan (mjordan) 2012-02-28 07:59:19.518-0600

Thanks for your comments. This does not appear to be a bug report and we are closing it. We appreciate the difficulties you are facing, but it would make more sense to raise your question in the support tracker, http://www.asterisk.org/support.  Alternatively, you can contact the asterisk-users mailing list or ask your question in #asterisk.

By: Dmitry Melekhov (slesru) 2012-02-28 21:42:54.664-0600

I'm pretty sure this _is_ bug, just because asterisk doesn't work as T38 gateway..

By: Dmitry Melekhov (slesru) 2012-02-29 00:28:46.132-0600

btw, played with res_fax.conf
if I set maxrate=7200 fax machines try (and fail) 9600 anyway.
Why? If limited ti 7200? looks like bug...

So I set maxrate=4800 and modems=v27.
Faxes pass....

Looks like problems with V29...