Anything that says “Open Source” is thought to be freely available, customizable and really exciting for many software users. (Specially people from India who are very price competitive, but I am sure Open source software sounds tempting to people all over the world!) Open Source alternative for any popular application software has almost become a industry practice and specialised Software, IVR too followed the same with some CTI vendors providing open source IVR platform for developers.

Thus Asterisk has almost become synonymous with Open Source IVR as well as Telephony Systems. Many companies have developed numerous Telephony solutions based on Asterisk.

While Open Source has many backers and takers, a newbie may still be confused when to choose Open Source
IVR or Telephony Application! First let us look at what one saves by using Open Source Telephony platform :-

A typical IVR System consists of the following components:-
1. Application Software ( IVR Call Flow)
2. Operating System/ Database
3. CTI Cards
4. PC or Server

By using Open Source Telephony platform, one saves #1 and #2 above! But is it a significant saving for you in the long term ?

1. According to me, one should choose Open Source if a company has spare manpower who is proficient in Linux and good in Linux based programming Languages. Many start up companies where the founders are normally engineers with programming background may choose Open Source IVR as they would be able to maintain the IVR without any extra cost! But for a company which may have to dedicate one or two manpower to develop and maintain the IVR systems, it may not be beneficial at all, in the long run!

2. Another advantage of choosing Open Source IVR is, the CTI cards seem to be less costlier than the CTI cards which have APIs. It is majorly because of the fact that, these CTI boards use host PC’s computing resources and does not have on-board DSPs to perform all those telephony signalling, audio processing. So if one is really constrained by budget, one may choose Open Source Telephony platform.

Some people are die hard fans of Linux and Open Source. For them, it is natural to choose Open Source IVR. But they should consider few things below :-

Other than Traditional Open Source ( Linux OS + Asterisk or FreePBX), there are IVR toolkits too available which provide the Toolkit free of cost and charges just per channel licenses at deployment! For example, VBVoice IVR Toolkit is freely downloadable along with 2 channel free license!

Apart from this kind of “offline” Tool kit, now a days, almost every company provides IVR in Cloud! Here anyone can design an IVR in a visual tool online and use as per usage!

Hope this may help how and when to choose an open source IVR!

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 ?