One of the major problem faced by any IVR developer using analog CTI board is “Detecting Disconnect” after call is hung up by IVR caller. With different disconnect tones used by different PBX manufacturer does not help either.

Detecting Call End or Disconnect is very easy while using digital CTI board with digital interfacing like ISDN, SS7 etc., but detecting DISCONNECT is not that straight forward or easy while using analog CTI boards. It is mainly because of exchanging “control information” with analog technologies!

There are few techniques or information using which DISCONNECT event can be detected and Call End process can be initiated in any CTI application:-

1. Disconnect Tones
This is most widely used information which is used by all PBX systems in the world. In analog telephone call scenario, in India, called party can not hang up the telephone call. It is the calling party which can disconnect the call and when he disconnects the call, PBX generates some “Disconnect Tones” which is recognised by CTI board and may send an event accordingly to the CTI application.
Normally, a “Disconnect Tone” vary from one PBX to another. But they follow same pattern, some Tone with fixed freqency for few seconds, then silence very short period, then again tone with another frequency, short silence, again first frequency, short silence. This sequence of “Tone1-Silence-Tone2-Silence” continues for some time and the line goes completely silence.

There are many tools available to get these frequencies and duration of tones, silence. Dialogic provides PBExpert ( requires two telephone extensions or telephone lines) which can be used directly to configure its driver to detect disconnect tone. One may also record the “Disconnect Tone” and find out its frequency, duration of silence, duration of tone period and then use them in the CTI programs to detect Call Disconnect event. CoolEdit, Audacity are few sound software which can give you information about frequency in sound file as well as duration.

Detecting CALL DISCONNECT using these “disconnect tones” are slow ( takes 10 to 30 seconds) and may not work with 100% accuracy. Also, many times, busy tone and disconnect tones in PBX systems tend to be same or similar. With recent introduction of CRBT ( Caller Ring Back Tone), task of detecting Disconnect Tone has been made more difficult!

2. Loop Current Drop

This is another method of detecting DISCONNECT condition while using Analog CTI boards. Many PBX systems use Loop Current Drop or Loop Reversal which is detected by analog CTI boards and pass on to CTI applications. Many analog CTI boards may not support this facility and many modern PBX too stopped this feature.

3. Using Timer in CTI application

One of the widely used “Call End” condition is detecting silence or time out waiting for caller input in the form of DTMF key pressing or Speech. This is easy to implement, independent of any PBX, but it is time consuming and tend to be very slow.

So, best way to detect call disconnect while using analog CTI boards would be to us hybrid of techniques mentioned above. And the best method, according to me is to use digital CTI boards, but this may not be possible always, though!

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.

There are few basic difference between outbound and inbound IVR Application. Normal IVR Application deals with inbound calls and call transferring. But an outbound IVR performs the few more tasks than an Inbound IVRS! And this is purely call handling point of View.

Though inbound application may have to do more computation as it has wider applications. But outbound calls have greater challenges in development. Here are few points to ponder about developing an outbound IVR Software:

1. Outbound calls may encounter various called parties! For example, the number dialed may turn out to be FAX number, so as soon as your call gets connected, IVR will get a FAX tone! So IVR has to detect FAX tone and and take appropriate action! It is specially important where outbound calls are payable as well as the usage time needs proper recording! It may face not only FAX, but also voice mail, answering machine, call forwarding etc.

2. Starting the message ( playback audio file ) after connection is very crucial! For example, if you detect FAX tone, you need to disconnect, not play the message! Same for Voice Mail, Answering Machine.

3. Deciding the type of card is also important. According to me, digital cards are better suited that analog cards. Here by digital cards, I am meaning digital interface like ISDN, R2MF, SS7! CTI cards are of course digital! Digital CTI boards can perform better in detecting FAX tone, Voice Mail, Answering Machine! Also, they give quick disconnection which important for call accounting.

4. Call synchronization is important. As outbound IVR Application will dial out multiple number simultaneously and some calls will be unsuccessful, which need to be retried! These kind of mechanism should be important and properly taken care of.

Few Features which are useful in an outbound IVR Application:

1. Outbound IVR application should have call transfer facility as an option just like inbound IVR application.

2. It should also have called party interaction through DTMF or Speech recognition.

3. The messages should be short and quick.

Arguably, Dialogic D4/PCI analog card must be the most widely used CTI card in the world! Also, most probably again, all 4 Generation Visual Tools for developing IVR Application supports this Dialogic D4/PCI CTI Card.

This card is easy to install, very feature rich, and has many advanced call processing feature. The most problematic part of any analog card s detecting engage tone, busy tone, ring back tone, apart from detecting Pulse Dialing! Amazingly this card has all those call processing feature which can be utilised effectively to solve these problems.

For those who are interested in know complete details, click here.

Here are few tips about using this card:-
1. Find out if your EPABX/Telecom Service provider has enabled Loop current drop at end of call. If not, ask them to enable so that you do not face Call Disconnect Not detecting problem. ( I feel, this is the most widely encountered problem by all IVRS people.)
2. You must create TSF file using PBXpert. This utility comes with Dialogic System Release, all versions. This tool makes few incoming/outgoing calls with two extension lines ( if EPABX) and train itself to detect the Engage Tone, Busy Tone and disconnect Tone, Ring Cadence etc. This step is very important.
3. To make your life easier, check for various PRM files in dialogic directory.

Finally, if nothing seems working, join www.dialogic.com/den/ and shoot your question in the forum. Or you can contact me.