The Voice Web: Commercial Implications of VoiceXML

By William Meisel

The Voice Web is convenient shorthand for the extension of the graphical Web to voice, particularly to wireless and wired telephones. The Voice Web is made practical by speech recognition, supported by text-to-speech synthesis and speaker verification in some applications. Speech recognition allows a flexible and more natural user interface, removing the limitation of the touch-tone keypad as the primary telephony user interface.

We are accustomed to viewing the Web via a Graphical User Interface, typically a Web browser on a PC. It is thus easy to conceptualize the Web as being what we see. The Web consists of a distributed data, most of which is interpreted through a graphical Web browser. While much of this data is currently represented in HTML code, in the future the data will be separated from presentation style using XML technologies. One can also think of scripts that describe rules for handling the data and user input as another form of data.

The Voice Web is a way of using that data and those rules through a voice dialog. In most cases, the way we will get at that data for voice will be quite different than how we do so for a graphical Web browser, but the data is the same. With this broad view, the commercial importance of the Voice Web will become more obvious. As we will see in the remainder of this article, the Voice Web is much more than just an extension of the visual Web.

VoiceXML and the Voice Web

VoiceXML is as important to the Voice Web as HTML was to the development of the visual Web. It provides a "voice view" of Web data and transactions that is independent of the various "voice browser" implementations that interpret the VoiceXML and the speech engines and telephony interfaces that underlay the voice browser. The costs of running the voice browser can be supported by a "voice portal" that is separate from the site on which the VoiceXML code resides-just as a user's graphical Web browser supports the cost of rendering HTML on the user's computer screen.

Another key advantage of VoiceXML is its simplicity. A large number of developers can readily master it, particularly those that have web development skills. Its support by many speech technology vendors will also encourage development of higher-level development programs that compile into VoiceXML, but allow the specification of dialogs in more friendly ways (as has occurred with HTML).

The Voice Web is growing rapidly, even without the full maturation of the VoiceXML language and VoiceXML interpreters. Nevertheless, a standard is critical for the Voice Web to meet its full commercial potential. At the moment the VoiceXML language specification is progressing under the efforts of the W3C Voice Browser Working Group.

Business Opportunities

There is a hierarchy of opportunity created by the Voice Web (see Figure 1). A company can occupy one or more of the segments shown. For example, a voice hosting company can simply provide a platform for delivering voice services that is shared by many companies for efficiency. That same voice hosting company is also likely to offer professional services to help customers develop applications. It may even develop proprietary tools that accelerate development to give it an edge over rivals.

VoiceXML probably fits best in the middleware category; in the sense that it provides a platform that isolates application software from the speech technology and voice transport (the telephone network). Nevertheless, it impacts all the other categories. Vendors in these categories must decide if they want to support VoiceXML, or perhaps even build their business based on VoiceXML. For example, a vendor of application software must decide whether to build applications in VoiceXML or use another, perhaps proprietary, application programming interface and a standard programming language.

To those cognizant of the long-term advantages of VoiceXML, the choice might seem obvious. But, today, VoiceXML developers tend to rely on proprietary extensions to take full advantage of features in most technology vendors' software. This will change as the technology stabilizes and VoiceXML matures, but when to adopt it is currently a difficult decision for many developers

Continued...

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