hah ... as steve was saying, studying libs/spandsp and checking out some functions within mod_t38gateway may also help with some understanding.... noone is stopping you from adding t38 support. On Tue, 15 Sep 2009, Steve Underwood wrote:

On 09/15/2009 02:51 PM, daqiang wang wrote:

...

how are you!

I want to add t38 support for mod_fax. Can anyone give me some suggestion ? Thank you very much ! Nobody is stopping you.

Steve

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SpanDSP already does it... someone just has to hook it all up. /b On Sep 15, 2009, at 8:10 AM, Jan Berger wrote:

Better to read the specs first if you want to dig into these algorithm's.

Jan

Steve Underwood ha scritto:

mod_t38gateway is little more than a place marker right now. Looking at how the T.38 engines in spandsp are used in Callweaver might be a better starting point. FS currently lacks a UDPTL transport, but the code for that is available (I'm not sure if ts in SVN, but it exists). It all needs dragging together.

mod_fax is 95% ready to accept t.38. The main missing parts, the last time i had a look at the problems are: - support for UDPTL in mod_sofia that lacks the code to parse and generate it - (eventually add t.38 over RTP in mod_sofia, but i have not yet seen any commercial/free switch that does manage it) - rework switch_rtp to accept t.38 packets to an application. - A way to signal an application that the channel supports T.38 (because, for example, mod_fax can be used on wanpipe - no t.38 and on sip) - A way to force a switchover to t.38, sent from the application to the channel driver (if supported) (because mod_fax may request a t.38 switchover to sofia or t38gw may request one leg to switch to t.38) - A way to signal the application that a switchover to T.38 has occurred on the channel driver (because the remote party may switch to t.38 and the endpoint application must take care of this) For the last 3 points, i have no idea how to do it in a clean and elegant way. Max