Implementing traditional voice mail using analog CTI boards is quite tricky. If the switch of EPABX does not support certain features, than it is almost impossible to implement traditional voice mail system with traditional operation. The major issue is finding out information of caller ID.
In a traditional voice mail system as I explained in the previous post, Voice Mail System and Answering Machine, it becomes difficult to provide two caller ID to the voice mail system. For example, C is the extension line to which voice mail system connected. Now if A calls B, B does not pick up so needs to transfer the call to C. So now C needs both caller ID, A and B, in order to store voice mails of B from A.
Voice Mail System using analog CTI board:
Voice mail systems are built in with EPABX or telephone exchanges. One can build a Voice Mail System using a simple 4-port analog CTI board and a PC. To build voice mail system, one will need the following hardware:-
1. A PC with one PCI slot free to install the analog CTI board.
2. Operating System to be installed on the PC as per driver availability for the CTI board. I think, only Dialogic provides driver for multiple or all operating systems for its CTI boards.
3. A database. Microsoft Access is a good option for Windows based PC and smaller voice mail systems. For large voice mail systems, either MS SQL or Oracle is recommended.
4. One 4 port CTI board
5. Four telephone lines of extension lines of EPABX
5. VMS software
VMS software is nothing but an IVR application which will record voice with caller ID and time stamp. And it will also playback the recorded voice messages as per owner or recipient of the voice mail messages over telephone. The recipient of the voice mail can also manage his messages like delete, purge etc.
Now, how to solve the the caller ID problem ?
The simplest way is to program the EPABX such a way that, when B ( as per above scenario) dos not reply, call A should be forwarded to C with caller ID of both A and B clubbed together with # as separator between the two! But, does the EPABX support this kind of intelligent programming ? If it does not, than most probably, you can not implement a voice mail system using analog card. You will have to use a digital CTI board where you will get these information easily. SS7 is the best as you get maximum information about the call.
There are few work around. For example :-
1. To ask the caller enter his number using DTMF. It may be little difficult for the caller and time consuming, but it is good option.
2. Map every voice mail account to every port of the analog CTI board. For example, port 1 of the CTI board will record messages only for B as in example above. This will requre some programming in the EPABX, but this is workable solution. The only problem will be future increase of number of users! But if number of voice mail users is large, one should never opt for analog CTI board!
Actually, implementing voice mail system using CTI board and IVR software has many advantages over built in VMS in the EPABX. For example :-
Customization of voice mail system become much easier. New prompts, call flow of voice mail can be changed, upgraded much easier and quicker.
2. Many enhancements and features
Many enhancements and features could be added to voice mail system. For example, as soon as a voice mail is received for particular VMS user, SMS alert can be sent to him. Email alert along with the voice message itself could be sent to him immediately. In fact, it can be integrated with outbound IVR System which will dial out to the voice mail user, play the mail, give options to reply! This kind of simple application was marketed in India as voice SMS quite successfully by many mobile operators!
3. Stored voice mail can be hard by local LAN as well as remotely over telephone. Better MIS and usability can be increased.
So, voice mail system with CTI board and smart IVR application can add many enhancements, killer features to any voice mail system. UMS ( Unified messaging system) is an example of such application.