[asterisk-dev] T38 gateway - consultation

[Steve Underwood]

Daniel Ferenci wrote:
> Hi Asterisk Developers,
>
> I would like to continue with my T38 gateway patch. 
> (https://issues.asterisk.org/view.php?id=13405)
> Currently the T38 gateway patch offers just explicit gatewaying. User 
> should exec faxgateway application for particular extension.
>
> There were requests for transparent gatewaying.
> The case:
> 1. at some point Asterisk bridges channels A and B
> 2. Later asterisk receives T38 request on channel A (for example by 
> reinvite)
> 3. Asterisk determines it can not pass this request to channel B 
> because B reports it does not support T38 at all.
> 4. At this point Asterisk decides to start T38 gateway for A-B 
> communication
>
> I got couple of ideas how to implement this request.
> Since I'm not the best knewledgable asterisk developer I would like to 
> discuss possible solutions with you.
> Mybe there is better solution I was not able to find.
>
> 1. add T38 gatewaying to app_dial
> (I think this would be feasible)
That's definitely feasible. We did that in Callweaver, though we kept it 
as a separate app for historic reasons. That app has all the 
functionality of app_dial, though.
> 2. add T38 gatewaying as a new bridge or update current bridging
> (yet I don't discover any way how to implement T38 gatewaying inside 
> bridge but maybe you can provide me by hints how to do it in this way)
It isn't really a bridging function. I never thought that model was a 
good fit.
> 3. add T38 as codec
> (this is probably not feasible at all)
T.38 is inherently bidirectional. Codecs are normally single 
directional, and Asterisk's codec model certainly is. T.38 just doesn't fit.

Doesn't Asterisk have some kind of bidirectional media processing 
chainable module framework these days? If so, T.38 gateway could 
certainly fit into that kind of framework.
>
> Can you please comment those possibilities and provide me by hints?
> Or can you come up with any other possibility?
Steve