[asterisk-users] T.38 on a MAX/Lucent/Ascend TNT

[Miguel Amez]

Hi!

I have probed t38modem several times without success.
The most I get was sending with t38modem and terminate faxes on a third-part
reseller, but with low bandwith sync between t38modem and my asterisk. it
syncs at 2400 bpps.
So If we (you and me) could get a working configuration for this, It will be
great.
I've wrote this list several times asking for this issue without any answer.

If you wonna collaborate, please tell me.

Regards,
Miguel Amez

2010/6/24 Ben Winslow <winslowb at pa.net>

> Hello folks,
>
> I've been trying to get T.38 over SIP working with calls terminated by a
> MAX/Lucent/Ascent TNT.  As far as I can tell, SIP and T.38 are actually
> working perfectly; however, I can't get the TNT to properly terminate a
> FAX call.  Does anyone have a working configuration for SIP and T.38 for
> calls from a TNT or APX?
>
> Here's a brief description/diagram of my test setup:
>
> Laptop --RS232--> Modem --POTS--> Channel bank (ADIT 600) --CAS T1-->
> TNT --Ethernet/SIP--> Asterisk --SIP--> t38modem.
>
> The TNT is running TAOS 11.0.4 with both the SIP and realtime fax
> features licensed.  I've tried using several modems, and with each I can
> establish a data call without any problems (although at a maximum of
> 31200bps/3429 baud using a 33.6 modem, for reasons I haven't dug into
> yet.)  Whenever I try to send a fax from the laptop, however, the call
> always seems to fail in the first HDLC phase (phase B) with either a
> timeout or error 23 (COMREC invalid command received.)  The modem is
> connected directly to the channel bank and the channel bank is connected
> directly to the TNT in an attempt to reduce the number of variables.
>
> With my current configuration, the call to Asterisk will come up as a
> voice call, then be dumped into t38modem when Asterisk receives the
> 1100Hz CNG tone from the sending modem.  At that point, the call is
> dumped into t38modem which re-invites the TNT with the T.38 options, and
> the TNT usually sends a T.38 t30-ind of 0x00 (no-signal) or 0x3a (???),
> although I do occasionally see more promising messages like
> v29-7200-training or t30-data/hdlc-fcs-ok.  Shortly thereafter, the
> dialing modem will give up and terminate the call.
>
> If I try dumping the same call into iaxmodem instead of t38modem, the
> call actually progresses further -- the real modem receives and decodes
> the HDLC CSI/DIS from iaxmodem, but the high-speed trainup always fails
> for calls coming from the TNT.
>
> Does anyone have any advice or suggestions?  Has anyone actually made
> T.38 work with one of these devices running ANY TAOS version?
>
> Thanks,
> --
> Ben Winslow <winslowb at pa.net>
>
> --
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