[asterisk-users] T.38 passthru on 1.8.5

[Steve Underwood]

On 08/31/2011 01:15 AM, Fabian Borot wrote:
> will installing spandsp help with t.38 pass-through?
The only part of spandsp which is relevant to T.38 passthrough is its 
modem tone detection module, and I don't think the standard Asterisk 
distribution can make use of that. Some people do use it, to overcome 
the limitations in Asterisk's own tone detection, but I don't think they 
make their patches available.

Steve
>
> ------------------------------------------------------------------------
> From: fborot at hotmail.com
> To: asterisk-users at lists.digium.com
> Subject: RE: T.38 passthru on 1.8.5
> Date: Tue, 30 Aug 2011 11:42:41 -0400
>
> both endpoints use public Ips, I just changed the real ones for the 
> privates ones to protect our ips but made a mistake and left the dest 
> as a pub and the orig as private, my bad.
> but for the record, both are public IPs, there is no nat and iptables 
> is off
>
>  also, I see that the quintum sends a lot of these packages but 
> asterisk sends only 1 or 2 to the other side.
>
>
>
>
>
> ------------------------------------------------------------------------
> From: fborot at hotmail.com
> To: asterisk-users at lists.digium.com
> Subject: T.38 passthru on 1.8.5
> Date: Tue, 30 Aug 2011 09:44:15 -0400
>
>
>  Hello
> We want to implement T.38 passthru with asterisk 1.8.5 [Asterisk 
> 1.8.5.0 built by root @ asterisk1-8.labdomain.com on a x86_64 running 
> Linux on 2011-08-26 21:31:22 UTC]
>
> The call flow is:
> quintum gateway --> asterisk --> Dialogic IMG 1010
>
> the call starts as a voice call, the remote fax picks up and we hear 
> the fax tone, the we see the re-invite from the IMG asking for t.38, 
> the RE-Invite is passed back to the user side [quintum gateway] whcih 
> reply with 200 OK with t.38 and the nothing else happens. After 20 
> secs of "inactivity" the quintum sends another Invite with voice only 
> and then a BYE.
>
> We do see that the quintum sends a lot of messages like this from the 
> quintum's IP [192.168.1.18] but we do not see that asterisk sends the 
> packages to the destination
>
> UDPTL (SIP/2345850624337933): packet to 192.30.189.146:12020 (type 0, 
> seq 0, len 6)
>  UDPTL (SIP/): packet from 192.168.1.18:10260 (type 0, seq 0, len 6)
>  UDPTL (SIP/): packet from 192.168.1.18:10260 (type 0, seq 0, len 6)
>  UDPTL (SIP/): packet from 192.168.1.18:10260 (type 0, seq 0, len 6)
>  UDPTL (SIP/): packet from 192.168.1.18:10260 (type 0, seq 0, len 6)
>  UDPTL (SIP/): packet from 192.168.1.18:10260 (type 0, seq 0, len 6)
>  UDPTL (SIP/): packet from 192.168.1.18:10260 (type 0, seq 0, len 6)
>  UDPTL (SIP/): packet from 192.168.1.18:10260 (type 0, seq 0, len 6)
>  UDPTL (SIP/): packet from 192.168.1.18:10260 (type 0, seq 0, len 6)
>  UDPTL (SIP/): packet from 192.168.1.18:10260 (type 0, seq 0, len 6)
>  UDPTL (SIP/): packet from 192.168.1.18:10260 (type 0, seq 0, len 6)
>  UDPTL (SIP/): packet from 192.168.1.18:10260 (type 0, seq 0, len 6)
>  UDPTL (SIP/): packet from 192.168.1.18:10260 (type 0, seq 0, len 6)
>  UDPTL (SIP/): packet from 192.168.1.18:10260 (type 0, seq 0, len 6)
>  UDPTL (SIP/): packet from 192.168.1.18:10260 (type 0, seq 0, len 6)
>  UDPTL (SIP/): packet from 192.168.1.18:10260 (type 0, seq 0, len 6)
>  UDPTL (SIP/): packet from 192.168.1.18:10260 (type 0, seq 0, len 6)
>  UDPTL (SIP/): packet from 192.168.1.18:10260 (type 0, seq 0, len 6)
>
> we have this settings on sip.conf
> faxdetect = yes
> t38pt_udptl = yes,maxdatagram=400 [I have tested with several 
> combinations t38pt_udptl = yes;t38pt_udptl = yes,fec etc]
>
> When we send the fax from the quintum to the Dialogic IMG the fax 
> works 100% of the times.
> I enabled fax set debug on and udptl set debug on but the console does 
> not show almost anything but the udptl packets shown above.
> What else should I do?Any ideas/help is greatly appreciated
>
> txs a lot
> fborot
>
>
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