[Asterisk-Dev] VoiceXML Connectivity for Asterisk

Steven Critchfield critch at basesys.com
Wed Dec 3 10:45:45 MST 2003

On Wed, 2003-12-03 at 06:59, Raj Kiran Talusani wrote:
> Hello all,
> I have seen a few people asking for VoiceXML support for Asterisk.
> We are developers of  Platform technologies in VoIP and Telephony
> space using the VoiceXML, SIP, CCXML etc standards.
> We have plans to write a connector module for Asterisk. That way
> our VoiceXML gateways will use Asterisk as the telephony platform instead
> of directly dealing with the Telephony Hardware. And i think if we do this
> we have to release source code for this module as GPL, and we are ok 
> with that.
> I think, we can do this in two ways. By writing a new channel 
> (chan_voicexml)
> or an application that can be called by asterisk at any time (app_voicexml).
> Which one would be better?

You mention above that you are using SIP. Why not just use SIP to
transport the call to your software? Then there is no code writing
needed unless there is SIP interop problems. 

If you do choose to write code, I'm not sure that a channel driver is
appropriate. A channel driver is a interconnection between end points
like PSTN, SIP, H323, IAX. These have the intention of delivering a call
to somewhere else.

An application is an end point for a call. Take a look at the meetme
app. It takes a call and end points it where it can mix in any number of
other audio components to serve back out.

You will probably end up making some form of IP based connection between
the asterisk application and the component you already have in place so
you can transmit certain meta data and the audio in both directions.
This is all available in the application space, and should be easily

> I didn't find any documentation explaining how to write a new channel or 
> a new
> application for Asterisk. If some can help me out with this i would 
> really appreciate.

Look at apps/app_skel.c This should get you the basics to get started.
Anything after that is just going to take looking at the other code
available to you and thinking about how best to interoperate with your
software already.

Steven Critchfield  <critch at basesys.com>

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