VoiceXML is an application of the Extensible Markup Language (XML) which, when combined with voice recognition technology, enables interactive access to the Web through the telephone or a voice-driven browser. An individual session works through a combination of voice recognition and keypad entry.
VoiceXML 1.0 was created through a collaboration of AT&T, IBM, Lucent Technologies, and Motorola, who were each working on their own approach but joined forces to create an open standard. Using XML, a programmer can enable voice recognition through the addition of a few simple tags.
VXML allows people with an ordinary voice telephone to access the Internet to get and send email, check sports scores, make reservations, and so on. VXML also can support natural language, which means that the user is not locked into a limited script, but can speak naturally. In what is called a "modeless" or "conversational" mode, the user can even interrupt the system with an out-of-context question and thus redirect the session. The goal is to make the exchange as natural as possible, as if two humans were interacting.
Here's an example of what VXML would enable a user to do: Pick up a phone, dial the number of the weather Web site, and request, for example, the weekend forecast. The voice request activates an XML query and then the query result is converted back to a voice message to give the user the information requested.