How to make PC to answer the incoming call?

Nov 3, 2008 at 6:47 AM

    I am doing an windows application using C4F Developer Kit...Out Going calls are working Perfectly...But while making the PC to answer Incoming call...There comes the problem...In TapiBase.cs....its not going to CALL_STATE.CS_OFFERING Case in CallEventMethod()....Can u please help me to solve this problem.....I have tried with your sample applications also....that is also not responding to incoming calls...Please Guide to solve this problem...Thank U...
Dec 5, 2008 at 11:37 AM
I too am having problems getting the Answer capability to work in the Tapi Sample Application.  When I run it I find that all of the controls within the PlaybackAndRecordingPanel are greyed out.  Do you find this also?

It seems to me that the application is NOT fully implemented.  I find methods defined in the AnsweringMachine.cs source called EnablePlayStopButtons(), EnablePlayBackControls() and EnableCallRecordingControls(), but there aren't any references to the methods (i.e. they're not CALLED from anywhere that I can find).

I have spent a fair amount of time looking at the Telephony project and debugging the TapiBase.cs source code.  I find that the error handling leaves much to be desired.  In many cases he has a block of code that looks like the following (see below).  He's essentially throwing away valuable debugging information and replacing it with a general "COM Exception" message.  In some cases, the errors that arise are not even COM-related, so it's an invalid assumption.

His code:
    do something with tapi;

catch (Exception exception)
    throw new TapiManagerException(Resources.ComException, exception);

I have found it necessary to replace the above catch with the following:


catch (Exception ex)




throw new TapiManagerException(ex.Message, ex);



Having done so, I'm currently trying to track down the source of the following error which I NOW see when I try to answer an incoming call:

"Unable to cast COM object of type 'System.__ComObject' to interface type 'TAPI3Lib.ITBasicCallControl'.  This operation failed because the QueryInterface call on the COM component for the interface with IID '{some unintelligible GUID}' failed due to the following error:  No such interface supported (Exception from HRESULT: 0x80004002 (E_NOINTERFACE))."