An Introduction to VoiceXML
Welcome to the first of a series of articles on VoiceXML, an XML technology that is driving many of the phone based services that you may well be already using. If you’ve ever called the airlines to check the status of your flight, dialed 1.800.FANDANGO for a movie location or ordered a pizza from 1.800.DOMINOS, you’ve already experienced the magic of VoiceXML.
The origins of VoiceXML go back to 1995, when a team at AT&T Bell Labs began looking at how to use the Internet to deliver voice applications. The result was a project called PhoneWeb. When AT&T spun off its Lucent division, a separate Phone Web project continued at both companies, followed by a third competing project at Motorola.
In 1998, a W3C conference on voice browsers led to the creation of the VoiceXML Forum, which was a consortium that included AT&T, Lucent, Motorola and IBM to coordinate the fragmented phone markup world and to define a standard dialog design language that developers could use to build conversational applications. XML was chosen as the basis for the common language, and in 2000 it became a W3C standard, followed by VoiceXML 2.0 in 2004.
When paired with a VoiceXML—compliant voice server, VoiceXML becomes a powerful, declarative, domain-specific language for speech applications. The capabilities of VoiceXML include the following:
- Synthesized speech (text-to-speech, TTS)
- Audio file playback
- Recognition of spoken input
- Recognition of touchtone input (referred to as DTMF)
- Recording of spoken input
- Control of dialog flow
- Telephony features such as call transfer and disconnect
When integrated with a backend database, VoiceXML can prove to be a powerful tool in its own right or as a powerful add-on to other services. In a world where multifaceted web service–based mashups are changing how we think of application development, VoiceXML brings a compelling voice dimension to the application service space. Using voice to communicate with the more than 4 billion cell phones expected to be operational by 2010 opens the door to new ways of delivering personalized customer experiences.