[asterisk-users] Digium FFA + Gafachi T38 outgoing issues

[Kevin P. Fleming]

On 10/07/2011 02:20 PM, James Sharp wrote:
> On 10/07/2011 12:27 AM, Nasir Iqbal wrote:
>> Check firewall and NAT settings!
>>
>> Monitoring sip and media flow from asterisk cli can help, use "sip set
>> debug on", "rtp set debug on" and "udptl set debug on"
>>
>
> No NAT involved and I shut off IPTables. Still no luck. Debug shows the
> SIP invite, RTP frames going in & out, the SIP reinvite, and then UDPTL
> frames coming in until timeout.
>
> See the entire transaction at http://pastebin.ca/2087758

Thanks for that; it helps.

First, we can see that Gafachi's T.38 implementation still has some 
breakage in it (although the problems are ones that Asterisk has been 
taught to deal with). In its 200 OK to the T.38 re-INVITE, it has 
"a=T38FaxRateManagement:transferredTCFlocalTCF"; this is not valid (the 
valid values for this are 'transferredTCF' and 'localTCF'). In addition, 
even though Asterisk sent "a=T38FaxUdpEC:t38UDPRedundancy", Gafachi 
replied with "a=T38FaxUdpEC:t38UDPFEC". For T.38 version 0 (which is in 
use here), the only valid response was either what Asterisk sent, or no 
T38FaxUdpEC value at all.

However, it is unlikely those are causing the call failure here. It's 
hard to say for sure without seeing the contents of the UDPTL packets, 
but based on their sizes, they are very likely "t38-nosignal" packets, 
and if that's all the FAX stack in Asterisk ever received, it would not 
trigger a FAX transaction to begin. Another possible problem is the 
repeated 'seq 0' in all the UDPTL packets, but this could be a problem 
with the UDPTL stack debugging messages themselves (this was just fixed 
in the Subversion branches for Asterisk 1.8 and later a couple of days ago).

If you would, please retry this with the HEAD of the Asterisk 10 branch 
instead of 10.0.0-beta1, and also capture the UDPTL packets themselves 
so we can see what they contained.

-- 
Kevin P. Fleming
Digium, Inc. | Director of Software Technologies
Jabber: kfleming at digium.com | SIP: kpfleming at digium.com | Skype: kpfleming
445 Jan Davis Drive NW - Huntsville, AL 35806 - USA
Check us out at www.digium.com & www.asterisk.org