Introduction to VoiceXML

If you are new to the idea of writing Voice-enabled telephone applications, then this is the place to start. What follows will give you the broad overview of what the VoiceXML markup language can do, and more importantly, what it cannot do. We will cover the basic building blocks of VXML, the core theories of design, and give you an idea of where to start and where to look for the information that you will need at your fingertips when coding voice applications on the Voxeo network.

What is VoiceXML?

And then along came the VoiceXML markup language.

VoiceXML allows the average web developer to write telephony applications with the ease and simplicity of writing the avaerage HTML web page. As VXML is a tag-based markup language, its structure is very similar to HTML in many ways, but instead of being a primarily visual medium, VoiceXML is an auditory medium that allows the end user to navigate through his 'telephony page' by using voice commands, rather than by clicking a button on a web page. Intrigued? Read on....

HTML versus VXML

How it Works

Creating a Voiceweb application on the Voxeo platform is easier than you might think. Sticking with our HTML versus VXML analogy, lets look at how HTML pages are served up, and compare it to how VXML pages get executed by your callers. When designing an HTML page, like our example above, we first author the document, and then upload it to our webserver so that it is publicly available for the whole world to see.

VoiceXML works with the same general principles, but with a slightly different spin, as we are using the telephone as the browser; Vo iceXML content must reside on a public webserver so that our servers can see it. The first difference is that while webhosts commonly serve up HTML, there aren't that many folks in the telephony game, so you will have to specifcally associate a phone number from a voice gateway, (us), and map it to the URL where your VXML page resides.

The next point is in how documents are fetched and executed. When a user clicks a link to our 'angry grandpa' HTML page, a request is sent to the webserver hosting the document, and the HTML page will then load the page in the user's web browser with the accompanying picture of a really angry 'golden ager'.

Again, VoiceXML works on the same principles, but remember that we are using the telephone as our web browser. Instead of clicking on a link, a user will dial the number pointing to your application, which is the equivalent of a hyperlink in HTML. When this number is dialed, it tells our servers to fetch the document that has been associated with that particular phone number or PIN code. Assuming that the code is well formed XML, and that the mapping has no typos, then our AngryGrandpa.xml file will load and execute, thus outputting the text to speech message to the caller.

What Will We Learn?

The Voxeo VoiceXML Guide is broken down in a pretty simple format. Preceding each hands-on, how-to module, you will find a short introduction that explains the principles of each tutorial in detail.

By the time you have completed the Lessons in the Voxeo VXML guide, you should have a solid handle on the following topics:

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