Voice applications have been very popular for years. We've all phoned in to verify a checking account balance, make note of an airplane arrival time, or hit "0" to speak to someone now (!) as opposed to wading through umpteen different options. VoiceXML was designed to standardize development of these types of applications, as well as to provide a standard platform for the construction of the "Voice web," an information web based not on HTML but on structured XML. In fact, an entirely new breed of service providers has already arisen to take advantage of this capability. These voice portals (as they are known) provide a toll-free number that members can call to retrieve a variety of information. This information currently includes restaurant info, movie times, driving directions, stock quotes, news, traffic information, and even daytime drama (that is, "soap opera") updates. Leading voice portals currently include TellMe Networks (http://www.tellme.com/ or 1-800-555-TELL) and BeVocal (http://www.bevocal.com/ or 1-800-4BVOCAL). Another upstart, Quack.com, was recently purchased by AOL. Thanks to this acquisition, AOL now offers voice access to email and other AOL features (1-800-AOL-1234).
For businesses that need to deliver quick snippets of information to their customers or employees (stock quotes, customer addresses, part information, and so on), VoiceXML is designed to be integrated within a "traditional" Web infrastructure. In simple terms, this means that a user can dial up your application and select (via keypad or voice) the option of interest. When this option is selected, your VoiceXML app can call a standard CGI script (or any other back-end server process). When the data is returned, the text-to-speech engine running on your server processes the returned data and "reads" it back to the end user. As VoiceXML is XML-based, it's entirely possible to use an XML technology such as XSLT (eXtensible Markup Language Transformation) to tailor a core set of XML content for a variety of devices (WML, HTML, VoiceXML, and so on).