Whats is legacy IVRS and what is VoiceXML based IVR System ?

Legacy IVRS
Legacy IVRS can be defined as the IVR Software installed on a personal computer and is developed using available native CTI Card APIs. The IVR software is developed for one CTI brand and model and the IVR Software may not work for any other CTI board or even model. Also, this type of IVR Software depends on the telephony interface used between CTI board and telephone exchange.
Legacy IVR software is supposed to control both the telephone interface part as well as VUI ( Voice User Interface). IVR software developer is supposed to be well versed with API provided by one particular CTI board as well as knowledgeable in switch technologies. Legacy IVR software performs every functionality in a interactive voice response system.

VoiceXML based IVRS
VoiceXML based IVR software can be defined as those IVR software which are written in VoiceXML. They normally deal with VUI(Voice User Interface) part of a interactive voice response system. VoiceXMX based IVR Software are neither dependent on CTI board/CTI Model nor interface with telephone switch. Any hardware interaction is performed by VoiceXML interpreter.
VoiceXML based IVR applications mainly deal with call flow of the IVRS. So, to write a VoiceXML based IVR software one may not require to know about CTI boards or any telecom switch!

Comparison
Both legacy IVRS and VoiceXML based IVRS have their own advantages and disadvantages. Though recently, many IVR companies are moving towards voiceXML based IVRS, there are still many die-hard legacy IVRS fans including me. Here I am trying to compare between legacy IVRS and voiceXML mased IVRS:

1. It is not easy to change call flow in a legacy IVR Software due to its strict dependence on CTI hardware used. But since VoiceXML based IVRS is independent of CTI boards, the call change is easy.

2. Programming in legacy IVRS is dependent on the CTI board, vendor and even model as well as the interface with telecom switch, but in case of VoiceXML, it is not dependent on those hardware.

3. VoiceXML based IVRS is much easier to develop as it is more like HTML for web portals and rightly they are said to be voice portals. Legacy IVRS is more difficult to develop as one has to learn about CTI board, its APIs and also its interfacing with telecom switch.

4. VoiceXML based IVRS is independent of operating systems used while legacy IVRS is dependent on operating system used.

5. VoiceXML is standard with fixed syntax. While legacy IVRS is not standardised in a sense that they are developed in wide variety of computer languages and platforms. Some use C++, some VB, some C language. Coding style may differ from one developer to another making it difficult for third-party to improve on a existing legacy IVRS.

Though, while developing VoiceXML based IVRS, one may not be dependent on CTI board or Telephony Interface used, but this is an disadvantage for a developer. They will be hostage to the VoiceXML interpreter. With many CTI manufacturer with various specification, it may not be easy for one VoiceXML interpreter to work on all CTI boards! So, it may not be correct to say that VoiceXML is totally independent of CTI boards.

In a legacy IVRS, developer has complete control of the software. So it is much easier in legacy IVRS to ingerate the IVR software with any other application which may not be possible in case of VoiceXML based IVRS. For example, in a call center, if there is already an existing CRM software and IVRS needs to be integrated with it, then most probably, VoiceXML based IVRS may not be able to integrate, but legacy IVRS can easily be integrated.

Both legacy and voiceXML has advantages and disadvantages. It will be wise to choose one among them as per requirements and usage. In some cases, voiceXML based IVRS may be better ( for example Voice Portal) while in scientific or specific application like medical applications, legacy IVRS is better suited.

My personal opinions.

There are many jargon used in IVRS World! When two IVR professionals discuss IVR Application or IVR Integration with EPABX or switches, most probably, many people as well as beginners in IVRS field might just be totally clueless what they might be blabbering! So I am compiling jargon related to IVRS (Interactive Voice response System).

1. IVR/IVRS : Interactive Voice Response System. This blog is all about IVRS.
2. CTI : Computer Telephony Integration, IVRS is a CTI application. Some variants of CTI are CTI Application, CTI Board, CTI Cards, CTI Hardware.
3. EPABX/SWITCH : EPABX stands for Electronic Private Automatic Branch Exchange. Another version is PABX ( Private Automatic Branch Exchange). Switch is same as EPABX but switch is much bigger, many more features.In fact it may not be right thing to compare EPABX and Switch. But IVRS has a very close relationship with them.
4. DIALOGIC : It is name of the company who is undisputed leader is CTI boards. It is almost synonymous with IVRS.
5. ISDN PRI : Integrated Services Digital Network Primary Rate Interface. It is an interfacing protocol between CTI Boards with EPABX/Switch.
6. ANI/CLI : Automatic Number Identification, Caller Line Identification. IVR Software can detect who is calling it! Other versions are : Caller ID, CLIP.
7. R2MF : R2 Line Signaling Multiple Frequency. It is another interfacing protocol between IVRS and Switch/EPABX. use of this interface is on decline.
8. DTMF : Dual Tone Multiple Frequency, used to choose option in IVRS by a caller.
9. VUI : Voice User Interface – It is the communication medium between human and IVRS by use of speech recognition or DTMF.
10. SS7 : Signaling System 7: Variant : CCS7. Most widely used interfacing protocol between IVRS and Switch. It has many advantages over other interfacing protocols as it gives more control as well as more information to the IVR Software. It gives IVR Developers more opportunities to develop varieties of IVR Applications to suit many industries. Normally SS7 CTI boards are costlier.
11. Inbound : Normally it means incoming calls to IVRS like inbound IVRS, when user calls in to the IVRS, it is an inbound IVRS.
12. Outbound : IVRS making outgoing calls to people. IVRS making outgoing calls to people and announce some news alerts, urge for vote a candidate in elections.
13. E1 : E1 Link/Line. E1 is 2.048 Mbit/s (full duplex) which is split into 32 time slots, used countries other than Japan and USA. Other similar jargon are E1 Modem, PCM line ( used mainly by BSNL, India).
14. T1 : T1 link/Line. T1 1.544Mbits, normally has 24 time slots. used by USA and Japan.
15. Call Flow : Flow chart of IVR Software, literally. Menus for IVR application, either speech driven or DTMF driven.
16. UMS : Unified Messaging Service, an interesting IVR Application.
17. CRM : Customer Resource Management, an integral part of call center, so it is related to IVRS. Most Call Center Software has IVRS and CRM as a part of it.
18. DNI : Dialed Number Identification. Mainly used in Voice Portal and CRBT
19. CRBT : Caller RingBack Tone, an revenue generating IVR Application with intelligent usage of SS7.
20. ASR : Automatic Speech recognition, used in Voice Driven Menu in IVR Software.
21. TTS : Text to Speech Converter. Used in IVRS to read out text in an IVR Software.
22. CDR : Call Data Record. Important in Voice Portal.
23. Engage Tone, Busy Tone, Disconnect Tone : Commonly heard while working on analog CTI boards with analog telephone lines.
24. Nokia, Siemens, Ericson : Switch Vendors.
25. MSP : Mobile Service Provider.
26. VoiceXML : Latest tool for developing voice portal.

There might more jargon out there and I will keep updating them here. Readers are welcome to add few of them here. Thank you in advance.