Fax polling service

FreeSWITCH Configuration
1

Hi,

I’m currently trying to set up a polling/retrieval service, where fax machines can call in a retrieve a file.
From the configuration samples and documentation I suspected the following snippet should work:

<include>
  <extension name="abruf">
    <condition field="destination_number" expression="^(1337)$">
        <action application="set" data="ignore_early_media=true"/>
        <action application="set" data="fax_ident=1337"/>
        <action application="set" data="fax_header=OHAI"/>
        <action application="set" data="fax_enable_t38=false"/>
        <action application="set" data="fax_verbose=true"/>  
        <action application="playback" data="silence_stream://2000"/>-->
        <action application="txfax" data="/tmp/loremipsum.tiff"/>
        <action application="hangup"/>
    </condition>
  </extension>
</include>

But that does not seem to work. An incoming call will get picket up but will time out while waiting for the fax handshake:

2024-12-12 01:11:17.358393 92.47% [DEBUG] mod_spandsp_fax.c:302 FLOW T.30 HDLC signal status is Carrier down (-1) in state T
2024-12-12 01:11:17.378391 92.47% [DEBUG] mod_spandsp_fax.c:302 FLOW T.30 HDLC signal status is Carrier up (-2) in state T
2024-12-12 01:11:17.378391 92.47% [DEBUG] mod_spandsp_fax.c:302 FLOW T.30 HDLC signal status is Carrier down (-1) in state T
2024-12-12 01:11:17.398377 92.47% [DEBUG] mod_spandsp_fax.c:302 FLOW T.30 HDLC signal status is Carrier up (-2) in state T
2024-12-12 01:11:17.398377 92.47% [DEBUG] mod_spandsp_fax.c:302 FLOW T.30 HDLC signal status is Carrier down (-1) in state T
2024-12-12 01:11:17.418381 92.47% [DEBUG] mod_spandsp_fax.c:302 FLOW T.30 HDLC signal status is Carrier up (-2) in state T
2024-12-12 01:11:17.418381 92.47% [DEBUG] mod_spandsp_fax.c:302 FLOW T.30 HDLC signal status is Carrier down (-1) in state T
2024-12-12 01:11:17.738368 92.70% [NOTICE] sofia.c:1065 Hangup sofia/external/2675@hg.eventphone.de [CS_EXECUTE] [NORMAL_CLEARING]
2024-12-12 01:11:17.738368 92.70% [DEBUG] mod_spandsp_fax.c:302 FLOW T.30 Status changing to ‘The call dropped prematurely’
2024-12-12 01:11:17.738368 92.70% [INFO] mod_spandsp_fax.c:596 ==============================================================================
Fax processing not successful - result (49) The call dropped prematurely.

I also played aroung with “fax_force_caller” but had no luck either.
Am I holding it wrong? Is it even possible to do what I want to achieve?
Or do I have to set some special flag because the polling machine is a German fax machine, not sure if machines in the US use another protocol for polling maybe?

Thanks :slight_smile:
Nico

2

try setting <action application="set" data="fax_enable_t38=true"/>
I’ve seen that if you also set a sound file, that can help.
<action application="playback" data="/path/to/your/soundfile.wav"/>

3

I explicitely disabled T.38 in my config because that caused more problems with the far-end than it helped but I’ll try the sound file.

Is is it even possible with freeswitch or did you test it with other systems? It looks like both systems (the calling fax and my freeswitch) seem to send a handshake but don’t “find” each other. Freeswitch is sending some very high pitched beeps, I haven’t heard these in fax context yet. Are there maybe different standards for different countries? I’m trying to do that with a German fax machine (and number).