[Freeswitch-dev] mod_fax

[Anthony Minessale]

I think i'm a bit overworked.

Steve is one of the small group of people I was mentioning above so I am not
sure why I am reminding him of the obvious.  We thank him profusely for his
involvement.


On Mon, Jan 5, 2009 at 8:17 AM, Anthony Minessale <
anthony.minessale at gmail.com> wrote:

> mod_fax is an unfunded work in progress so calling it crude means I guess
> we are not off to a very good start.
> Your input is nonetheless appreciated as the small group of 3 or 4 coders
> continue to try and find time to add t.30 and t.38 support to
> FreeSWITCH in our spare time with little or no help.  So eventually your
> concerns will probably be addressed but
> Rome was not built in a day........
>
> You do seem to have a talent for writing.  May I suggest your volunteer
> your skills on our WIKI?
> http://wiki.freeswitch.org/
>
>
>
>
>
> On Sun, Jan 4, 2009 at 9:21 AM, Steve Underwood <steveu at coppice.org>wrote:
>
>> Hi all,
>>
>> I finally started to play with mod_fax today. First, a couple of little
>> observations. Although there is a config file for fax, modules.conf.xml
>> doesn't contain an entry for mod_fax, and dialplan/default.xml doesn't
>> contain a demo like
>>
>>    <extension name="test_rxfax_stream">
>>      <condition field="destination_number" expression="^9011$">
>>    <action application="answer" />
>>    <action application="playback" data="silence_stream://2000"/>
>>    <action application="rxfax" data="rxfax.tif"/>
>>    <action application="hangup"/>
>>      </condition>
>>    </extension>
>>
>>    <extension name="test_txfax_stream">
>>      <condition field="destination_number" expression="^9012$">
>>    <action application="txfax" data="txfax.tif"/>
>>    <action application="hangup"/>
>>      </condition>
>>    </extension>
>>
>> as it does for other modules.
>>
>> For more serious things.....
>>
>> If the far end of a SIP FAX transaction sends a reinvite to switch to
>> T.38, FS sends a 488 back and everything fouls up. Other boxes send back
>> the previous codec as the new one to use, and everything carries on
>> smoothly in audio mode. I'm not a SIP expert, so I don't know the
>> details of what it says on the topic, but in the real world successful
>> continuance of a call requires a response other than 488. As an aside,
>> the called party should be the one to initiate an attempt to use T.38,
>> but in the real world the calling party often does.
>>
>> If T.38 is not available (which it isn't ever right now), and the call
>> starts with a low bit rate codec, we should initiate a reinvite to use
>> Alaw or ulaw. If that fails we might as well abandon the call.
>>
>> mod_fax currently follows the practice of my old and crude demo programs
>> for *, and has apps called rxfax and txfax. This is taking a very narrow
>> view of a FAX machine, and I think is too limiting. I think the
>> following is how things should be:
>>
>>    - One app, probably just called FAX.
>>    - It will be started with a flag saying if it should act as the
>> calling party or the called party.
>>    - The app will be given optional lists of files to send, and files
>> to receive.
>>    - The app will do its best to exchange all the files it can,
>> including the use of poll mode FAXing.
>>
>> The module documentation says page by page events should be added (which
>> spandsp supports), and this seems a sound idea. FAXback and other
>> services might be implemented through this.
>>
>> Regards,
>> Steve
>>
>>
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>
>
>
> --
> Anthony Minessale II
>
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>
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>



-- 
Anthony Minessale II

FreeSWITCH http://www.freeswitch.org/
ClueCon http://www.cluecon.com/

AIM: anthm
MSN:anthony_minessale at hotmail.com <MSN%3Aanthony_minessale at hotmail.com>
GTALK/JABBER/PAYPAL:anthony.minessale at gmail.com<PAYPAL%3Aanthony.minessale at gmail.com>
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