VoiceXML (VXML) is a digital document standard for specifying interactive media and voice dialogs between humans and computers. It is used for developing audio and voice response applications, such as banking systems and automated customer service portals. VoiceXML applications are developed and deployed in a manner analogous to how a
web browser
A web browser, often shortened to browser, is an application for accessing websites. When a user requests a web page from a particular website, the browser retrieves its files from a web server and then displays the page on the user's scr ...
interprets and visually renders the
Hypertext Markup Language
Hypertext Markup Language (HTML) is the standard markup language for documents designed to be displayed in a web browser. It defines the content and structure of web content. It is often assisted by technologies such as Cascading Style Sheet ...
(HTML) it receives from a
web server
A web server is computer software and underlying Computer hardware, hardware that accepts requests via Hypertext Transfer Protocol, HTTP (the network protocol created to distribute web content) or its secure variant HTTPS. A user agent, co ...
. VoiceXML documents are interpreted by a
voice browser {{Short description, Interactive voice user interface
A voice browser is a Application software, software application that presents an interactive voice user interface to the user in a manner analogous to the functioning of a web browser interpretin ...
and in common deployment architectures, users interact with voice browsers via the
public switched telephone network
The public switched telephone network (PSTN) is the aggregate of the world's telephone networks that are operated by national, regional, or local telephony operators. It provides infrastructure and services for public telephony. The PSTN consists o ...
(PSTN).
The VoiceXML document format is based on
Extensible Markup Language
Extensible Markup Language (XML) is a markup language and file format for storing, transmitting, and reconstructing data. It defines a set of rules for encoding documents in a format that is both human-readable and machine-readable. The Wor ...
(XML). It is a standard developed by the
World Wide Web Consortium
The World Wide Web Consortium (W3C) is the main international standards organization for the World Wide Web. Founded in 1994 by Tim Berners-Lee, the consortium is made up of member organizations that maintain full-time staff working together in ...
(W3C).
Usage
VoiceXML applications are commonly used in many industries and segments of commerce. These applications include order inquiry, package tracking, driving directions, emergency notification, wake-up, flight tracking, voice access to email, customer relationship management, prescription refilling, audio news magazines, voice dialing, real-estate information and national
directory assistance
In telecommunications, directory assistance or directory inquiries is a phone service used to find out a specific telephone number and/or address of a residence, business, or government entity.
Technology
Directory assistance systems incorporate ...
applications.
VoiceXML has tags that instruct the
voice browser {{Short description, Interactive voice user interface
A voice browser is a Application software, software application that presents an interactive voice user interface to the user in a manner analogous to the functioning of a web browser interpretin ...
to provide
speech synthesis
Speech synthesis is the artificial production of human speech. A computer system used for this purpose is called a speech synthesizer, and can be implemented in software or hardware products. A text-to-speech (TTS) system converts normal langua ...
, automatic
speech recognition
Speech recognition is an interdisciplinary subfield of computer science and computational linguistics that develops methodologies and technologies that enable the recognition and translation of spoken language into text by computers. It is also ...
, dialog management, and audio playback. The following is an example of a VoiceXML document:
When interpreted by a VoiceXML interpreter this will output "Hello world" with synthesized speech.
Typically,
HTTP
HTTP (Hypertext Transfer Protocol) is an application layer protocol in the Internet protocol suite model for distributed, collaborative, hypermedia information systems. HTTP is the foundation of data communication for the World Wide Web, wher ...
is used as the transport protocol for fetching VoiceXML pages. Some applications may use static VoiceXML pages, while others rely on dynamic VoiceXML page generation using an
application server
An application server is a server that hosts applications or software that delivers a business application through a communication protocol. For a typical web application, the application server sits behind the web servers.
An application ser ...
like
Tomcat,
Weblogic
Oracle Fusion Middleware (FMW, also known as Fusion Middleware) consists of several software products from Oracle Corporation. FMW spans multiple services, including Java EE and developer tools, integration services, business intelligence, co ...
,
IIS, or
WebSphere
IBM WebSphere refers to a brand of proprietary computer software products in the genre of enterprise software known as "application and integration middleware". These software products are used by end-users to create and integrate applications w ...
.
Historically, VoiceXML platform vendors have implemented the standard in different ways, and added proprietary features. But the VoiceXML 2.0 standard, adopted as a W3C Recommendation on 16 March 2004, clarified most areas of difference. The VoiceXML Forum, an industry group promoting the use of the standard, provides a
conformance testing
Conformance testing and also known as compliance testing or type testing, is testing or other activities that determine whether a process, product, or service complies with the requirements of a specification, technical standard, contract, or reg ...
process that certifies vendors' implementations as conformant.
History
AT&T Corporation
AT&T Corporation, an abbreviation for its former name, the American Telephone and Telegraph Company, was an American telecommunications company that provided voice, video, data, and Internet telecommunications and professional services to busi ...
,
IBM
International Business Machines Corporation (using the trademark IBM), nicknamed Big Blue, is an American Multinational corporation, multinational technology company headquartered in Armonk, New York, and present in over 175 countries. It is ...
,
Lucent
Lucent Technologies, Inc. was an American multinational telecommunications equipment company headquartered in Murray Hill, New Jersey. It was established on September 30, 1996, through the divestiture of the former AT&T Technologies busines ...
, and
Motorola
Motorola, Inc. () was an American multinational telecommunications company based in Schaumburg, Illinois. It was founded by brothers Paul and Joseph Galvin in 1928 and had been named Motorola since 1947. Many of Motorola's products had been ...
formed the VoiceXML Forum in March 1999, in order to develop a standard markup language for specifying voice dialogs. By September 1999 the Forum released VoiceXML 0.9 for member comment, and in March 2000 they published VoiceXML 1.0. Soon afterwards, the Forum turned over the control of the standard to the W3C.
The W3C produced several intermediate versions of VoiceXML 2.0, which reached the final "Recommendation" stage in March 2004.
VoiceXML 2.1 added a relatively small set of additional features to VoiceXML 2.0, based on feedback from implementations of the 2.0 standard. It is backward compatible with VoiceXML 2.0 and reached W3C Recommendation status in June 2007.
Future versions of the standard
VoiceXML 3.0 was slated to be the next major release of VoiceXML, with new major features. However, with the disbanding of the VoiceXML Forum in May 2022,
the development of the new standard was scrapped.
Implementations
As of December 2022, there are few VoiceXML 2.0/2.1 platform implementations being offered.
*
Hewlett-Packard
The Hewlett-Packard Company, commonly shortened to Hewlett-Packard ( ) or HP, was an American multinational information technology company. It was founded by Bill Hewlett and David Packard in 1939 in a one-car garage in Palo Alto, California ...
(OCMP)
*OnMobile (Ozone Speech Platform)
*
Alvaria
*
Avaya
Avaya LLC(), formerly Avaya Inc., is an American multinational technology company headquartered in Morristown, New Jersey, that provides cloud communications and workstream collaboration services. The company's platform includes unified commun ...
(Avaya Experience Portal)
*
OpenVXI
*
Cisco
Cisco Systems, Inc. (using the trademark Cisco) is an American multinational digital communications technology conglomerate corporation headquartered in San Jose, California. Cisco develops, manufactures, and sells networking hardware, s ...
*
Genesys (company)
Genesys Cloud Services, Inc. (Genesys), formerly Genesys Telecommunications Laboratories, Inc., is an American software company that sells customer experience (CX) and call center technology to mid-sized and large businesses. It sells both cloud ...
*
Nuance Communications
Nuance Communications, Inc. is an American multinational computer software technology corporation, headquartered in Burlington, Massachusetts, that markets speech recognition and artificial intelligence software.
Nuance merged with its comp ...
*
Phonologies
*
Plum Voice
*Telesoft Technologies
Related standards
The W3C's Speech Interface Framework also defines these other standards closely associated with VoiceXML.
SRGS and SISR
The
Speech Recognition Grammar Specification
Speech Recognition Grammar Specification (SRGS) is a W3C standard for how ''speech recognition grammars'' are specified. A speech recognition grammar is a set of word patterns, and tells a speech recognition system what to expect a human to say. ...
(SRGS) is used to tell the speech recognizer what sentence patterns it should expect to hear: these patterns are called grammars. Once the speech recognizer determines the most likely sentence it heard, it needs to extract the semantic meaning from that sentence and return it to the VoiceXML interpreter. This semantic interpretation is specified via the
Semantic Interpretation for Speech Recognition
Semantic Interpretation for Speech Recognition (SISR) defines the syntax and semantics of annotations to grammar rules in the Speech Recognition Grammar Specification (SRGS). Since 5 April 2007, it is a World Wide Web Consortium recommendation.
...
(SISR) standard. SISR is used inside SRGS to specify the semantic results associated with the grammars, i.e., the set of ECMAScript assignments that create the semantic structure returned by the speech recognizer.
SSML
The
Speech Synthesis Markup Language
Speech Synthesis Markup Language (SSML) is an XML-based markup language for speech synthesis applications. It is a recommendation of the W3C's Voice Browser Working Group. SSML is often embedded in VoiceXML scripts to drive interactive telephony sy ...
(SSML) is used to decorate textual prompts with information on how best to render them in synthetic speech, for example which speech synthesizer voice to use or when to speak louder or softer.
PLS
The
Pronunciation Lexicon Specification
The Pronunciation Lexicon Specification (PLS) is a W3C Recommendation, which is designed to enable interoperable specification of pronunciation information for both speech recognition and speech synthesis engines within voice browsing application ...
(PLS) is used to define how words are pronounced. The generated pronunciation information is meant to be used by both speech recognizers and speech synthesizers in voice browsing applications.
CCXML
The
Call Control eXtensible Markup Language
Call Control eXtensible Markup Language (CCXML) is an XML standard designed to provide asynchronous event-based telephony support to VoiceXML. Its current status is a W3C recommendation, adopted May 10, 2011. Whereas VoiceXML is designed to provid ...
(CCXML) is a complementary W3C standard. A CCXML interpreter is used on some VoiceXML platforms to handle the initial call setup between the caller and the voice browser, and to provide telephony services like call transfer and disconnect to the voice browser. CCXML can also be used in non-VoiceXML contexts.
MSML, MSCML, MediaCTRL
In
media server
A media server is a computer appliance or an application software that stores digital media (video, audio or images) and makes it available over a network.
Media servers range from servers that provide video on demand to smaller personal compu ...
applications, it is often necessary for several call legs to interact with each other, for example in a multi-party conference. Some deficiencies were identified in VoiceXML for this application and so companies designed specific scripting languages to deal with this environment. The
Media Server Markup Language (MSML) was Convedia's solution, and
Media Server Control Markup Language (MSCML) was Snowshore's solution. Snowshore is now owned by Dialogic and Convedia is now owned by Radisys. These languages also contain 'hooks' so that external scripts (like VoiceXML) can run on call legs where
IVR functionality is required.
There was an IETF working group called ''mediactrl'' ("media control") that was working on a successor for these scripting systems, which it is hoped will progress to an open and widely adopted standard. The mediactrl working group concluded in 2013.
See also
*
ECMAScript
ECMAScript (; ES) is a standard for scripting languages, including JavaScript, JScript, and ActionScript. It is best known as a JavaScript standard intended to ensure the interoperability of web pages across different web browsers. It is stan ...
– the scripting language used in VoiceXML
*
OpenVXI – an open source VoiceXML interpreter library
*
SCXML
SCXML stands for State Chart XML: State Machine Notation for Control Abstraction. It is an XML-based markup language that provides a generic state-machine-based execution environment based on Harel statecharts.
SCXML is able to describe compl ...
– State Chart XML
References
External links
W3C's Voice Browser Working Group Official VoiceXML Standards
VoiceXML Forum VoiceXML Trademark Holder
VoiceXML tutorials
{{DEFAULTSORT:Voicexml
World Wide Web Consortium standards
XML-based standards
Markup languages
Speech synthesis
XML-based programming languages
VoIP protocols
2000 software