"Definitive VXML" book: code examples: Interesting numerous VXML examples from the book "Definitive VXML"
Ecmascript language specification (ECMA-262): The ECMAScript language that is used by VXML to provide client-side scripting capabilities. Compact profile ECMA-367 is used within SRGS grammars to support semantic interpretation.
Ken Rehor's World of VoiceXML: Comprehensive index of VXML resources and events maintained by Ken Rehor, the "principal founder of the VoiceXML Forum"
Palowireless VoiceXML Resource Center: VoiceXML Resources including conferences, articles, news, development tools, market research, technology, tutorials.
Semantic Interpretation for Speech Recognition (SISR): The specifications which describes how tags within SRGS grammars may be inserted to support basic post-processing or full semantic interpretation. This is then used by VXML to support advanced features such as mixed initiative.
Speech Recognition Grammar Specification (SRGS) Version 1.0: The W3C specifications used by VXML to enable speech recognition
Speech Synthesis Markup Language (SSML) Version 1.0: The W3C specifications used by VXML to provide speech synthesis.
Voice Browser Call Control: CCXML Version 1.0: The upcoming call control language for more elaborate control than VXML transfer. CCXML uses VXML to specify dialogs with connected call parties.
Voice category at developer.com: Voice-technology related tutorials and articles including introduction to VXML, natural vs directed dialogs, SRGS and CCXML introductions
Voice Extensible Markup Language (VXML) version 1.0: Official note specification; designed for creating audio dialogs that feature synthesized speech, digitized audio, recognition of spoken and DTMF key input, recording of spoken input, telephony, and mixed-initiative conversations. (W3C Note 05 May 2000)
Voice Extensible Markup Language (VXML) Version 2.0: Pointer to the latest 2.0 specification including new errata published by the W3C consortium.
Voice Extensible Markup Language (VXML) Version 2.1: The pointer to the latest 2.1 draft specifications including errata. Version 2.1 is a minor refinement of 2.0 with features that are simple, already implemented by some vendors, and not already available within 2.0 version.
VoiceXml Yahoo Group: VoiceXml user group at Yahoo. Includes discussions and experiences with VoiceXML syntax and applications.
VoiceXML Forum: Organization dedicated to promoting VXML. Main activities include developer and platform certifications, education (tutorials and newsletters), and tools fostering. Delegates VXML standardisation to W3C. Hosted by IEEE-ISTO.
VoiceXML Italian User Group.: Italian site which regroups the VoiceXML users. Includes tutorials, articles and links to VXML resources (in Italian and in english).
VXML Tutorial for Perl Programmers: WebReference.com's tutorial on VoiceXML, entitled "Tellme More."
W3C's Introduction to VoiceXML 2.0: A nice VXML tutorial provided by Dave Raggett to the W3C. A great introduction to VXML with code samples.
W3C: Voice Browser Activity: Portal of the activity of the W3C Voice Browser Working Group including public mailing list, links to current status, work under development, links to drafts and specifications, FAQs.
XHTML+Voice Profile 1.0 (W3C Note): XHTML+Voice profile is designed for Web clients that support visual and spoken interaction.