[Freeswitch-users] t38_gateway hangs up non-deterministic with normal clearing

[Roman Dissauer]

this is our topology:

customer pbx <-> kamailio + rtpengine <-> several FreeSWITCH Machines <-> kamailio <-> several interconnection carriers

what we have to address for inbound/outbound calls:
inbound call comes from any interconnection carrier which mostly does NOT have t.38 faxing what is no issue because we have reliable internet lines to our carriers. Our customers want to have t.38 faxing because of reliability of faxing over standard internet lines. So we have to transcode g.711a codec to t.38 in freeswitch. Same is true for outbound calls where customer pbxes send t.38 re-Invite but the upstream interconnection carrier does not accept t.38.

sometimes faxing is fine with this mechanism but mostly the fax is rejected by a „NORMAL CLEARING“ as soon as the re-Invite is coming in. FreeSWITCH is sending BYE to both call legs.

what we intend to do with our dialplan on an example - incoming calls

1. call is coming in via external profile with g.711a Codec
2. set refuse_t38=true sets t38 to be rejected coming from a-leg - external carrier
3. export fax_enable_t38=true will enable t38 both call legs
4. export nolocal:sip_execute_on_image=t38_image=t38_gateway self nocng will enable t38 only on b-leg - customer side
5. call is being bridged to kamailio where it gets routed to the customer

thank you!

best regards,
Roman

> Am 04.12.2019 um 14:02 schrieb Giovanni Maruzzelli <gmaruzz at gmail.com>:
> 
> On Tue, Dec 3, 2019 at 11:19 PM Roman Dissauer <roman at dissauer.net <mailto:roman at dissauer.net>> wrote:
> we have an issue with t38_gateway where calls which should be transcoded from PCMA to t38 get hangup non-deterministic. It doesn’t matter if there is only one call or if there are hundrets of calls on the freeswitch. Sometimes it happens that we get several faxes transcoded but then we again have several faxes which don’t go through. problem exists (tested) on FreeSWITCH 1.6 and FreeSWITCH 1.10.
> 
> this is the dialplan section where t38_gateway is set up for b-leg on an inbound call:
> 
> <context name="hosted_numbers">
>          <extension name="43732601458-DDI" continue="true">
>             <condition field="${outside_call}" expression="^true$" break="never"/>
>             <condition field="${dialed_extension}" expression="^(43732601458)(\d{0,4})$“>
>                ...
>                <action application="set" data="refuse_t38=true"></action>
>                <action application="export" data="fax_enable_t38=true"></action>
>                <action application="export" data="nolocal:sip_execute_on_image=t38_gateway self nocng"></action>
>                <action application="bridge" data="{sip_cid_type=pid,sip_contact_user=accountcode,absolute_codec_string='PCMA at 20i,PCMU at 20i,G729'}sofia/internal/accountcode at 10.23.101.10 <mailto:accountcode at 10.23.101.10>^+${dialed_extension}@10.23.101.10 <mailto:dialed_extension%7D at 10.23.101.10>"></action>
>                ...
>             </condition>
>          </extension>
>       </context>
> 
> 
> 
> Would you detail, line by line, what is the intended purpose of each line of dialplan?
> 
> Also, your topology, and the intended result
> 
> -giovanni
> 
> _________________________________________________________________________
> 
> The FreeSWITCH project is sponsored by SignalWire https://signalwire.com <https://signalwire.com/>
> Enhance your FreeSWITCH install with disruptive priced SMS and PSTN services.
> Build your next product on our scalable cloud platform.
> 
> Join our online community to chat in real time https://signalwire.community <https://signalwire.community/>
> 
> Professional FreeSWITCH Services
> sales at freeswitch.com <mailto:sales at freeswitch.com>
> https://freeswitch.com <https://freeswitch.com/>
> 
> Official FreeSWITCH Sites
> https://freeswitch.com/oss <https://freeswitch.com/oss>
> https://freeswitch.org/confluence <https://freeswitch.org/confluence>
> https://cluecon.com <https://cluecon.com/>
> 
> FreeSWITCH-users mailing list
> FreeSWITCH-users at lists.freeswitch.org <mailto:FreeSWITCH-users at lists.freeswitch.org>
> http://lists.freeswitch.org/mailman/listinfo/freeswitch-users <http://lists.freeswitch.org/mailman/listinfo/freeswitch-users>
> UNSUBSCRIBE:http://lists.freeswitch.org/mailman/options/freeswitch-users <http://lists.freeswitch.org/mailman/options/freeswitch-users>
> https://freeswitch.com <https://freeswitch.com/>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.freeswitch.org/pipermail/freeswitch-users/attachments/20191206/b336ffad/attachment-0001.html>