[Freeswitch-users] t.38 Call Flow Information

Sat Dec 22 04:12:56 MSK 2012

Hi Anthony,
I got successful transmission working.  
I'm testing like this:
Fax Machine --> Linksys SPA-3102 --t.38-- > FS1 --audio --> FS2 (rxfax)
In analyzing the logs its seems FS2 was reporting the ECM was negotiated where the t38 side from was negotiating ECM off because the Linksys adapter doesn't do ECM.  By explicitly disabling ECM on the receiving end (FS2) everything is working.  Should it not negotiate ECM off all the way through?

Also, I'm still seeing late re-invites so I tried to do:
<action application="set" data="execute_on_answer=t38_gateway self nocng"/>

That fails with:
2012-12-21 17:00:19.617866 [WARNING] mod_spandsp_fax.c:1578 sofia/default/1002 at 10.59.1.195 Cannot locate channel with uuid f4b7afd8-4bd2-11e2-b9db-2fac9796034a

I took a look at mod_spandsp.c and can find any reason why that wouldn't work.  Am I missing something or should I file a jira?  The strange thing is that I use nocng with sip_execute_on_image and it works fine.

On Dec 21, 2012, at 2:34 PM, Anthony Minessale wrote:

> if you dont need actual detection you can skip it with nocng and jump right into the processing,  
> You'll have to eyeball it but it should detect it right away, take note of it by watching the logs.
> 
> 
> 
> On Fri, Dec 21, 2012 at 4:22 PM, Spencer Thomason <spencer at 5ninesolutions.com> wrote:
> I tried tweaking this and it didn't seem to have any effect.  I'm calling t38_gateway like this:
> <action application="set" data="execute_on_answer=t38_gateway self"/>
> before the bridge.
> 
> Is there anything I should be doing to speed up the detection?  I should note that is on the receiving end.
> 
> The re-invite from rxfax worked without a hitch.  Would this suggest the default req_counter value is ok?
> 
> 
> On Dec 21, 2012, at 9:12 AM, Anthony Minessale wrote:
> 
>> you can tweak mod_spandsp_fax.c:1391
>> 
>> req_counter is how many packets to wait before sending re-invite.
>> 
>> You can play with reducing this number and if its effective it could be made into a configurable param.
>> 
>> 
>> 
>> On Fri, Dec 21, 2012 at 10:42 AM, Spencer Thomason <spencer at 5ninesolutions.com> wrote:
>> Hi Steve,
>> That was my take as well.   I've posted packet captures and logs here:
>> http://jira.freeswitch.org/browse/FS-4957
>> 
>> Is there any way to speed up the ReINVITE?
>> 
>> Thanks,
>> Spencer
>> 
>> 
>> -----Original message-----
>> From: Steve Underwood <steveu at coppice.org>
>> To: freeswitch-users at lists.freeswitch.org
>> Sent: Fri, Dec 21, 2012 09:57:07 GMT+00:00
>> Subject: Re: [Freeswitch-users] t.38 Call Flow Information
>> 
>> Hi,
>> 
>> It looks like your reinvite occurred extremely late, and the FAX was 
>> already deep in progress as an audio exchange.
>> 
>> Steve
>> 
>> 
>> On 12/21/2012 03:14 AM, Spencer Thomason wrote:
>> > Hello,
>> > I've been analyzing some Wireshark traces to get a better grasp on the t.38 gateway process. I'm using t38_gateway to convert SIP t38 to TDM audio on the receiving end. I'm struggling to understand the following call flow. I've excluded the audio portion for brevity but t38 is negotiated correctly by both endpoints (FS on our end and Acme on the other). Note the absence of a DIS message and the PPS prior to CFR. Can anyone shed any light on this?
>> >
>> > Thanks in advance,
>> > Spencer
>> >
>> >
>> > Acme FreeSWITCH
>> > |1716.691635| INVITE SDP (t38) | |SIP Request
>> > | |(5060) <------------------ (5070) | |
>> > |1716.719556| 100 trying -- your call is important to us | |SIP Status
>> > | |(5060) ------------------> (5070) | |
>> > |1716.830431| | no-signal | |t38:t30 Ind:no-signal
>> > | | |(21440) <------------------ (15876) |
>> > |1716.906132| 200 OK SDP (t38) | |SIP Status
>> > | |(5060) ------------------> (5070) | |
>> > |1716.912839| ACK | | |SIP Request
>> > | |(5060) <------------------ (5070) | |
>> > |1716.973011| | no-signal | |t38:t30 Ind:no-signal
>> > | | |(21440) ------------------> (15876) |
>> > |1717.450595| | v21-preamble |t38:t30 Ind:v21-preamble
>> > | | |(21440) <------------------ (15876) |
>> > |1717.730869| | PPS | |t38:v21:HDLC:Partial Page Signal
>> > | | |(21440) <------------------ (15876) |
>> > |1717.780811| | no-signal | |t38:t30 Ind:no-signal
>> > | | |(21440) <------------------ (15876) |
>> > |1718.130798| | v17-14400-long-training |t38:t30 Ind:v17-14400-long-training
>> > | | |(21440) <------------------ (15876) |
>> > |1719.541095| | t4-non-ecm-data:v17-14400 |t38:t4-non-ecm-data:v17-14400 Duration: 1.51s No packet lost
>> > | | |(21440) <------------------ (15876) |
>> > |1721.060850| | no-signal | |t38:t30 Ind:no-signal
>> > | | |(21440) <------------------ (15876) |
>> > |1722.573572| | v21-preamble |t38:t30 Ind:v21-preamble
>> > | | |(21440) ------------------> (15876) |
>> > |1723.593652| | CFR | |t38:v21:HDLC:Confirmation To Receive
>> > _________________________________________________________________________
>> > Professional FreeSWITCH Consulting Services:
>> > consulting at freeswitch.org
>> > http://www.freeswitchsolutions.com
>> >
>> > 
>> > 
>> >
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>> >
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>> >
>> 
>> 
>> _________________________________________________________________________
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>> consulting at freeswitch.org
>> http://www.freeswitchsolutions.com
>> 
>> 
>> 
>> 
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>> 
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>> 
>> 
>> _________________________________________________________________________
>> Professional FreeSWITCH Consulting Services:
>> consulting at freeswitch.org
>> http://www.freeswitchsolutions.com
>> 
>> 
>> 
>> 
>> Official FreeSWITCH Sites
>> http://www.freeswitch.org
>> http://wiki.freeswitch.org
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>> 
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>> 
>> 
>> 
>> -- 
>> Anthony Minessale II
>> 
>> FreeSWITCH http://www.freeswitch.org/
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>> 
>> AIM: anthm
>> MSN:anthony_minessale at hotmail.com
>> GTALK/JABBER/PAYPAL:anthony.minessale at gmail.com
>> IRC: irc.freenode.net #freeswitch
>> 
>> FreeSWITCH Developer Conference
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>> googletalk:conf+888 at conference.freeswitch.org
>> pstn:+19193869900
>> _________________________________________________________________________
>> Professional FreeSWITCH Consulting Services:
>> consulting at freeswitch.org
>> http://www.freeswitchsolutions.com
>> 
>> 
>> 
>> 
>> Official FreeSWITCH Sites
>> http://www.freeswitch.org
>> http://wiki.freeswitch.org
>> http://www.cluecon.com
>> 
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> 
> 
> _________________________________________________________________________
> Professional FreeSWITCH Consulting Services:
> consulting at freeswitch.org
> http://www.freeswitchsolutions.com
> 
> 
> 
> 
> Official FreeSWITCH Sites
> http://www.freeswitch.org
> http://wiki.freeswitch.org
> http://www.cluecon.com
> 
> FreeSWITCH-users mailing list
> FreeSWITCH-users at lists.freeswitch.org
> http://lists.freeswitch.org/mailman/listinfo/freeswitch-users
> UNSUBSCRIBE:http://lists.freeswitch.org/mailman/options/freeswitch-users
> http://www.freeswitch.org
> 
> 
> 
> 
> -- 
> Anthony Minessale II
> 
> FreeSWITCH http://www.freeswitch.org/
> ClueCon http://www.cluecon.com/
> Twitter: http://twitter.com/FreeSWITCH_wire
> 
> AIM: anthm
> MSN:anthony_minessale at hotmail.com
> GTALK/JABBER/PAYPAL:anthony.minessale at gmail.com
> IRC: irc.freenode.net #freeswitch
> 
> FreeSWITCH Developer Conference
> sip:888 at conference.freeswitch.org
> googletalk:conf+888 at conference.freeswitch.org
> pstn:+19193869900
> _________________________________________________________________________
> Professional FreeSWITCH Consulting Services:
> consulting at freeswitch.org
> http://www.freeswitchsolutions.com
> 
> 
> 
> 
> Official FreeSWITCH Sites
> http://www.freeswitch.org
> http://wiki.freeswitch.org
> http://www.cluecon.com
> 
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