CONNECTED event not firing in TAPI 3.x

I am working on a TAPI application. While googleing I found a nice post http://www.code开发者_如何转开发project.com/KB/IP/devangpro.aspx. But the problem is, I am not getting all the events triggered while making a call. I am able to get INPROGRESS and DISCONNECTD but no CONNECTED event is getting fired (even in the screenshot provided with the article, only "dialing" and "disconnected" values are present, so I am assuming even the author had the same problem). In my case whole program logic is based on the CONNECTED and DISCONNECTED events. Please help me to solve the issue.

Also, I am using a CISCO ATA box for obtaining dial tone. I tried with a FAX/DATA as well as FAX/DATA/VOICE modems.

As far as I can see from the code sample, it uses the TAPI3.dll by automatically creating an Interop wrapper through VS.Net. But the use of TAPI3 from managed code is not supported by Microsoft. See this KB article:

Because of the complexity of the TAPI 3.x Component Object Model (COM) interface, the managed wrapper that is created by Microsoft Visual Studio .NET does not work. Therefore, you cannot call TAPI functionality from managed code.

Microsoft has no current plans to release a TAPI interoperative component.

You will have to use a wrapper around TAPI 3.x to use it in managed code. For this, you could for example use JulMar's ITAPI3 wrapper.