[cisco-voip] IOS version for t.38?

[Christopher]

Hello...

On Mon, 2008-12-15 at 14:22 +0100, Andre Beck wrote:
> Hi Christopher,
> 
> On Mon, Dec 08, 2008 at 01:22:16PM -0800, Christopher wrote:
> > Hello...
> > 
> > Summary: I am trying to implement t.38 for receiving faxes.  It doesn't
> > work and I suspect the IOS version I am using.  What is a "known good
> > version" for t.38?
> > 
> > Details:
> >    2821 router
> >    Version 12.4(15)T5  #   T train
> >      c2800nm-advipservicesk9-mz.124-15.T5.bin
> >    PRI incoming (2)
> >    GigE to local Call Manager servers
> >    4 Voice FXS interfaces
> 
> I've done my testing on essentially the same hardware, but running the
> latest IOS that was there at the time (12.4(22)T).
>    
> > One site, everything is local on a GigE network.  The phones all work.
> > Normal Faxes via FXS to a Hylafax server work.
> > 
> > If I call the phone number I am sending to the t38 modem, I do get a fax
> > tone.  However, when using a real fax machine, the error on the
> > receiving side is:  "Failure to receive silence (synchronization
> > failure)."  Tested (and every fax call failed) using t38modem on both
> > FreeBSD 6.3 and Linux (ubuntu).  When I use two t38 modems to "call"
> > each other I can connect fine.   
> 
> That's exactly my observation, too. I fear though that the real issue
> might be t38modem. Given the base this software is built upon (the R.I.P.
> OpenH323 mess), I don't really trust it to do things correctly. Then again,
> the issue might well be on the IOS side. When going into deep debugging,
> there is some state during the establishment of the fax connection when
> IOS constantly sends nothing put empty transport packets, but never joins
> the actual V.22something conversation.
>  
> > I have googled and searched the cisco site and everything I read points
> > to me doing everything correctly.
> 
> Though there is very little to be found when searching. There's a handful
> of postings, most of them talking about similar issues, and mostly they
> end in silence. I've got the impression that it might indeed not work
> that well except when talking to itself.


I saw the same, but I also saw many posts that referenced working
systems.  specifically cisco talking to t38modem to hylafax.


>  What version of t38modem did you
> test, the ones usually bundled with distros or the newer stuff that uses
> new VoIP stacks and can deal with SysV PTYs? I could only test with the
> one bundled in Debian stable (still beeing Etch today), which could be
> considered rather old.

I tested t38modem v0.8.4 from ubuntu 8.0.4 usually running in screen
with trace/debug options.

I also tested on freebsd 6.3 with t38modem 1.0.0 and 1.0.1 compiled with
versions of openh323/pwlib (the legacy code) or h323plus/ptlib_v2_0_1
(current).  All failed the same exact way except when talking to another
t38modem, hence me suspecting IOS, especially T versions.  ( I run
12.0(32)S11 on several VXR routers as I like old stable code :)



>  
> > dial-peer voice 489 voip
> >  description To VoIP fax
> >  destination-pattern 489
> >  session target ipv4:xx.yy.zz.20
> >  codec g711ulaw
> >  fax-relay ecm disable  # tried with and without
> >  fax rate 14400
> >  fax protocol t38 ls-redundancy 0 hs-redundancy 0 fallback none
> >  no vad
> 
> Looks like my dial-peer, I've done some testing with non-zero redundancy
> settings on both sides, but to no avail.
>  
> > Any ideas?
> 
> I was planning to test IOS against the Exchange 2007 T.38 implementation,
> but wasn't able to convince the Exchange admin yet. Googling some more,
> it appears that Exchange has broken T.38 in SP1 so a negative test will
> not be a final pointer. The next potential test target would be Cisco
> Fax server, but there's no demo/test download apparently. Considering that
> mess I dediced to do something else and come back to the holy war against
> faxes later ;)
> 
> If you find anything that makes t38modem work, I'm all ears.
> 

I was replacing a hylafax with an analog DID setup (we moved offices and
get a shinny new VoIP system).  I ended up ordering another Analog DID
line for the new office :(

With the number of Cisco people on this list, I am suprised none of them
chimed in.

  

> TIA
> Andre.
-- 
Christopher <chrismcc at pricegrabber.com>