What is VXML ?
VXML, also known as Voice XML is W3C(World Wide Consortium) standard for specifying voice interaction between human and a computer. So, it essentially is a ‘tool’ or high level level language for scripting an IVR ( Interactive Voice response) application. It can take input from human in the from of DTMF digits, automatic speech recognition (ASR) etc. Like standard XML, it consists of many ‘tags’ specific to voice applications which are accepted as standards by W3C.
Voice XML or VXML can be used to specify a call flow in an IVR application without having to learn about CTI boards, its integration with switches, PABX systems etc.

What is VoicePHP ?
VoicePHP is another “tool” for developing voice applications which mainly integrates IVR applications to web. It can be thought of an extension of widely popular PHP language to build voice specific same way as any web application is built!
VoicePHP is tool which seems to be in direct competition with VXML for specifying voice applications on web. VoicePHP is a product from tringme.

Both these tools provide ‘tools’ or ‘convention’ to specify or write voice applications or IVR applications, they differ from other RAD tools like Pronexus VBVoice, Envox CT AD in their intended usage. Most probably, these two “voice application” tools are aimed at developing or integrating IVR with many web applications. With recent growth in usage of outbound IVR application, these two tools may prove to be very useful for many people to integrate voice mail box in their blogs, websites which would be streamed live or delivered instantly to concerned person.
With this kind of tools in place, website visitor could get a call on his telephone by call center to learn more about products, service on the website as well as discuss specific requirements instantly.

While VXML is be endorsed by W3C, but writing complex voice application with dynamic content would not be too easy, it seems. But, it would be easy to build any interpreter which would actually implement the voice application as per the specification written in XML.

I was just wondering:-
1. What is the best way to specify a voice application ?
2. Do we need voice application to be modeled as any Web Applications ?
3. Could we model voice application to be embedded system with real time data exchange with many other applications as well as controlling of call flow ?
4. How would these “voice application tools” would keep up with CTI boards which are being upgraded constantly ?