What is a Voice Mail System (VMS) and a Answering Machine ?

Voice mail system can be thought as a message box for phone user to store voice messages and retrieve it through telephone. User can divert all his calls to his voice mail system when he wishes so.
Main difference between answer machine and voice mail system is that voice mail system is a centralized system where voice mail boxes are managed for many users, while answering machine is an independent individual system connected to a telephone line. Many telephone instrument comes with built-in answering machine.

Typicl picture of Answering Machine

Answering machine is usually suitable for home use for single line, while voice mail system is more suitable for office use where there are multiple telephone connections as well as extensions through EPABX.

A typical voice mail system operation:
A traditional voice mail system operates in the following way :
1. A dials B.
2. B is unable to attend the call. So call from A gets diverted to voice mail box of B.
3. Caller A hears a greetings from B welcoming him to mailbox of B and asks A to leave/record his voice message after a beep.
4. Once caller A speaks to record his voice message for B, he gets option to hear what he has recorded or hang up.
5. Next time whenever B lifts his phone, he gets to hear a message that he has an unheard voice message that can be heard by pressing some key.
6. If B is out of town, B can dial his voice mail box number ( a predefined number connected to voice mail system) to check if new voice mail has arrived. Then he can browse through his voice mails, listens them, delete them.

A Typical Answering Machine Operation:
1. A dials B.
2. After certain number of rings ( programmable or configurable), answering machine attached to the telephone of B gets activated and answers the call of A.
3. Answering machine greets A and asks to leave a message for B after beep.
4. A records his message and hangs up.
5. B can see a alert text message on his answering machine that a message is stored.
6. B presses a key on the answering machine and listens to it, can delete.

Normally, voice mail system is like an IVR system, invisible to the real user and resides somewhere else, normally at Telecom operator office. While answering machine is a small device attached to the telephone line lying nearby to the telephone instrument or inbuilt into the telephone instrument itself.

Many voice mail systems offer option to reply the voice mail sender through voice again, which is not possible in answering machine! Answering machine is being replaced by voice mail system as voice mail systems offer more features, accessibility.

Recently voice mail systems has developed into a powerful unified messaging solutions integrated with many other communication media line Email, SMS, FAX etc. thanks to smart implementation of IVR systems. I will be updating about it more in my next post about building smart voice mail system using a low cost 4 port analog CTI board.

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.