I think, analog CTI boards most problematic to configure other than simple incoming or inbound IVR Software. They are dependent on switch or PBX connected to them for many basic IVR functions, call operations. I am trying to list here the problems I had been facing while using analog CTI boards:-

1. Disconnect
2. Dial Tone
3. Dial out
4. Caller Id

1. Disconnect
You need to ‘define’ the disconnect tone to your IVR application so that it can detect disconnect. This disconnect tone may vary from PBX to PBX. Dialogic has a tool PBXpert to detect various analog tones like dial tone, disconnect tone, busy tone, ring back tone etc. With CRBT ( Caller Ring Back Tone) being popular now a days, detection of ring back tone has just become more difficult.

2. Dial Tone
Dial tone also varies from one PBX manufacturer to another. This dial tone becomes very important when you make an outgoing call. IVR application may be unable to make outgoing call if it fails to detect dial tone. Though there are ways to dial out without detecting dial tone or learn dial tone and feed in IVR application, it is still not easy.

3. Dial out
Once successfully dial out, it may not be easy to detect if dialled party has picked up the call. Many people use Call Progress Analysis to detect, if person has picked up the call. But I always think, it is not easy or it does not work accurately all the time.

4. Caller ID
Unlike in digital CTI boards or Digital Telephony interface, caller ID detection is almost a pain and it may not work accurately all the time. Normally, in analog interface with PBX, the caller id is sent by PBX in DTMF form after first or second ring. So, it is really cumbersome to detect Caller ID.

Digital CTI boards with digital interface does not have the above problems. So it would be nice if one can avoid using analog CT boards and use digital boards. Though digital boards are costlier, but now a days there are many CTI vendors which have digital CTI boards which are priced very competitive.

I have thought of an arrangement to avoid using analog CTI cards. Though it may make the IVR system costlier, but most probably, it will be good arrangement in terms of future enhancements, more features. My thinking is to use use a EPABX with PRI card. the CTI board will be connected to EPABX through E1 connectivity and use ISDN PRI protocol. Commonly used and widely available. In turn EPABX may have CO lines from telephone service provider ( analog lines which other wise you wold have connected to CTI board directly). This kind of EPABX may cost less than Rs. 150,000/-

Now, when price of 4 port CTI boards starts with Rs. 10,000/-, investing another Rs. 150,000 on a EPABX and another Rs. 30,000 for a digital CTI board, may not make sense, honestly! But there are some benefit of using this kind of arrangement for for specific IVR application and outbound IVRS is one of them, considering the cost of hiring a E1 link from telephone service provider.

But, the problems I have listed above can be solved by smartly writing your IVR software. In fact, they must be routine problems for many IVR developer, unfortunately no document is available on net, at least I could not Google it. And I am yet to write a smart IVR application for analog CTI board as I started my IVR software development with Dialogic D300 board and R2MF protocol!