[Freeswitch-users] T.38 and Audiocodes or Patton gateway

[Kristian Kielhofner]

Dave,

  It's a better parameter for T.38 in general...

  When you look at a T.38 trace (presumably without ECM) you'll see
that the T.38 data stream is entirely unidirectional.  The sending
device sends a stream of data - that's it.

  I first caught on to this with large faxes or faxes with high
complexity that took a while to send.  I finally found one fax page
with multiple images that failed 100% of the time when being sent from
FreeSWITCH to the device.  Once I set the rtp-timeout-sec parameter to
600 it succeeded 100% of the time.  This change was (and has been) the
single biggest change I've made to my configuration to improve my T.38
success rate.

  Ideally FreeSWITCH could be updated with an "enhanced understanding"
of the unidirectional flow of T.38 and modify/tweak/remove the RTP
timeout parameter as necessary (I imagine it does something similar
with silence suppression/CNG now).  Or maybe I'm completely wrong and
this change had no effect (I seriously doubt that).

On Tue, Nov 16, 2010 at 11:14 AM, Dave  Redmore
<dave.redmore at spigotsystems.com> wrote:
> I'm curious about your recommendation to use a long (600 sec) media/RTP
> timeout value in the sofia profile.  Is this a specific need for the
> Audiocodes device or just generally better for T.38?  I'm assuming you are
> referring to the "rtp-timeout-sec" parameter?
>
> I'm using FreeSwitch as a media proxy to a T38 provider and have had decent
> success, but usually have problems with longer faxes (8+ pages) and am
> wondering if this setting might help?
>
> Thanks,
>
> Dave Redmore

-- 
Kristian Kielhofner
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