[Opalvoip-user] WG: OPAL cannot handle comming Fax T.38/SIP from Avaya IPO

[Tobias S. <tob...@no...>]

Hi,

I am currently working on an application which uses OPAL for it's VoIP-Capabilities/Fax. Most of our functionallity is working as expected, but we ran into some truble when we tried to receive Faxes from an Avaya IPO 500 via T.38 over SIP.
Receiving Faxes from other PBX's(such as a Cisco Call Manager) is working fine :) T.30 is also working on IPO, we just have a problem with T.38.

We are using OPAL Version 3.10.9, ptlib Version v2.10.9 from svn tags and  the latest version of spandsp (spandsp-0.0.6pre21).
I am testing on a 64bit Windows 7 machine.

When we try to reiceive an incomming fax, OPAL answers the call and seems to recognize it as a T.38 Call(it sends an ACK). But it does not seem to reply any further after that ACK. The IPO 500 just continuiously sends it's cng's until it times out and send a BYE(which is answerd with an ACK from OPAL)

The unexpected behaviour can be triggered with opalfax.exe from the sample applications using the following commandline.

faxopal.exe --no-h323 -t -t -t -t -t -t -t -t -t -t -t -t -t -o "Trace.txt" fax.tiff

I have uploaded the Trace generated by the above call to faxopal.exe and a Wireshark-Capture, which shows that OPAL does not respond after the OK.
The IPO in the trace hast he IP 192.168.25.138 and the faxopal.exe is run on IP 192.168.25.106.

https://docs.google.com/file/d/0B9p1q0sjOFfBUUl1LVFxLUV6NlE/edit

https://docs.google.com/file/d/0B9p1q0sjOFfBdUoxZy16ZG54VmM/edit

I noticed, that the IPO 500 sends an INVITE with only T38 in it's capabilities, whereas other PBX's first establish a Voice-Transmission and later send a Re-INVITE to switch to T.38(or OPAL sends this Re-Invite).
Could it be piossible, that OPAL can not handle the case, when a fax transmission should be established via the initial INVITE?

Are there any switches that can be turned on to make OPAL accept such a call?
I tried any of the the following but none of those changed anything.
--no-audio
--no-fallback n
--switch-on-ced
--switch-time n

Are there any other options I a can try?

What else can I do to narrow down the problem? Any Ideas?

Does anybody else have a simalar problem?

Thank you for any help/hint or information regarding this problem.

Kind Regards
Tobias Stähli

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