[Freeswitch-users] SIP to TDM t38 gateway

[Spencer Thomason]

Hi Alex,
Thanks for your help.

The problem is I need to detect the fax tones in the audio stream and then send a ReINVITE.  I'm attempting to do this like this:

    <extension name="dial-pbx"> 
      <condition field="destination_number" expression="^(.*)$"> 
        <action application="set" data="fax_enable_t38=true"/> 
        <action application="set" data="fax_enable_t38_request=true"/> 
        <action application="set" data="execute_on_answer=t38_gateway self"/> 
        <action application="bridge" data="freetdm/1/a/$1"/> 
      </condition> 
    </extension>

The topology is like this:
Incoming Call:
ITSP ----SIP---> Freeswitch -----ISDN PRI----> Legacy PBX ----> Fax Machine
In this case I need to detect the fax and send a ReINVITE.
The media bug gets created as soon as the channel is answered but immediately gets destroyed. The fax tones are never detected and no reinvite is sent.


Outgoing call
Fax Machine ----> Legacy PBX ---ISDN PRI----> Freeswitch ---SIP---> ITSP
The ITSP sends a ReINVITE and when using sip_execute_on_image t38_gateway is working correctly.

See:
http://jira.freeswitch.org/browse/FS-4789
http://pastebin.freeswitch.org/20162

Were you able to get this working?

Thanks for your help!
Spencer


On Nov 22, 2012, at 9:21 AM, Alex Crow wrote:

> Hi Spencer,
> 
> I use this (gatewaying via a Mitel 3300 but there is no reason why it 
> would not work for FreeTDM, just change the bridge at the end).
> 
> 
>       <action application="set" data="absolute_codec_string=PCMU"/>
>       <action application="set" data="fax_enable_t38=true"/>
> <action application="set" data="sip_execute_on_image=t38_gateway self 
> nocng"/>
>       <action application="bridge" data="sofia/gateway/10.10.0.2/$1"/>
> 
> 
> Hope this helps if a bit late.
> 
> Cheers
> 
> Alex
> 
> On 05/11/12 21:32, Spencer Thomason wrote:
>> Hello,
>> I'm trying to use Freeswitch as a SIP to TDM gateway.  I'd like to use t38_gateway to detect fax tones and send a ReINVITE to t38.
>> 
>> Have a very minimal config with one profile that simply relays to FreeTDM
>> 
>> My dialplan is:
>> <include>
>>   <context name="sip">
>> 
>>     <extension name="dial-trunk">
>>       <condition field="destination_number" expression="^(.*)$">
>>         <action application="set" data="fax_enable_t38=true"/>
>>         <action application="set" data="fax_enable_t38_request=true"/>
>>         <action application="set" data="execute_on_answer=t38_gateway self"/>
>>         <action application="bridge" data="freetdm/1/a/$1"/>
>>       </condition>
>>     </extension>
>> 
>>   </context>
>> </include>
>> 
>> The problem is a media bug is created on the channel but almost immediately destroyed so fax tones are never detected.
>> 
>> See:
>> http://pastebin.freeswitch.org/20162
>> 
>> Thanks for any assistance,
>> Spencer
>> 
>> 
>> 
>> 
>> _________________________________________________________________________
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>> http://www.freeswitchsolutions.com
>> 
>> 
>> 
>> 
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> 
> 
> _________________________________________________________________________
> Professional FreeSWITCH Consulting Services:
> consulting at freeswitch.org
> http://www.freeswitchsolutions.com
> 
> 
> 
> 
> Official FreeSWITCH Sites
> http://www.freeswitch.org
> http://wiki.freeswitch.org
> http://www.cluecon.com
> 
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