How to use TAPI3.0 to make a call ?

Question

Operating environment:
 windows xp sp2
 CCME-TSP 

I want use VB.net to write a simple make call program. I follow the SDK example, write it like below. but I get the error:"
COMException was unhandled
Can't enumerate any more, because the associated data is missing (Exception from HRESULT: 0x80040002 (OLE_E_ENUM_NOMORE)) "  when I step to " objTerminal = objTerminalSupport.GetDefaultStaticTerminal(TAPIMEDIATYPE_AUDIO, TERMINAL_DIRECTION.TD_CAPTURE)" . I am a newbie. Could anyone give me some help or an example, thanks~

Code Snippet

Imports TAPI3Lib

Module Module1

    Public Const TAPIMEDIATYPE_AUDIO As Integer = &H8
    Public Const LINEADDRESSTYPE_PHONENUMBER As Integer = &H1

    Sub Main()
        'initialize
        Dim gobjTapi As TAPI = New TAPI
        gobjTapi.Initialize()

        'select address
        Dim gobjAddress As ITAddress
        Dim objCollAddress As ITCollection
        objCollAddress = gobjTapi.Addresses

        Dim bFound As Boolean
        bFound = False
        Dim objCtrAddress As ITAddress
        Dim objMediaSupport As ITMediaSupport

        Dim index As Integer
        For indexAddr As Integer = 1 To objCollAddress.Count
            objCtrAddress = objCollAddress.Item(indexAddr)
            objMediaSupport = objCtrAddress

            If objMediaSupport.QueryMediaType(TAPIMEDIATYPE_AUDIO) Then
                bFound = True
            End If

            If bFound = True Then
                index = indexAddr
                Exit For
            End If

            objMediaSupport = Nothing
            objCtrAddress = Nothing
        Next

        gobjAddress = objCollAddress.Item(index)

        'make a call
        Dim gobjCall As ITBasicCallControl
        gobjCall = gobjAddress.CreateCall("172015727", LINEADDRESSTYPE_PHONENUMBER, TAPIMEDIATYPE_AUDIO)

        'select the terminal
        Dim objCallControl As ITBasicCallControl
        objCallControl = gobjCall

        Dim objTerminalSupport As ITTerminalSupport
        objTerminalSupport = gobjAddress

        Dim objTerminal As ITTerminal
        objTerminal = objTerminalSupport.GetDefaultStaticTerminal(TAPIMEDIATYPE_AUDIO, TERMINAL_DIRECTION.TD_CAPTURE)

        objTerminalSupport = Nothing

        Dim objStreamControl As ITStreamControl
        objStreamControl = objCallControl

        If Not (objStreamControl Is Nothing) Then

            Dim objITCollStreams As ITCollection
            objITCollStreams = objStreamControl.Streams

            Dim nIndex As Long, objCrtStream As ITStream
            For nIndex = 1 To objITCollStreams.Count
                objCrtStream = objITCollStreams.Item(nIndex)
                If objCrtStream.MediaType = TAPIMEDIATYPE_AUDIO Then
                    If objCrtStream.Direction = TERMINAL_DIRECTION.TD_CAPTURE Then
                        objCrtStream.SelectTerminal(objTerminal)
                    End If
                End If
                objCrtStream = Nothing
            Next

            objITCollStreams = Nothing
            objStreamControl = Nothing
        End If
        'end  select terminal

        gobjCall.Connect(False)

        gobjTapi.Shutdown()

    End Sub

End Module

Answer 1

I change the codes, delete the portion"       

'select the terminal

        Dim objCallControl As ITBasicCallControl
        objCallControl = gobjCall
".
But, when it run at "objTerminalSupport = objAddressCapabilities", get the error message:
InvalidCastException was unhandled
Unable to cast COM object of type 'System.__ComObject' to interface type 'TAPI3Lib.ITTerminalSupport'. This operation failed because the QueryInterface call on the COM component for the interface with IID .


I guess differents between interface ITAddress and interface ITTerminalSupport cause this issue. How should I fix this issue ?

Code Snippet

Imports TAPI3Lib
Imports System.Threading

Module Module1

    Public Const TAPIMEDIATYPE_AUDIO As Integer = &H8
    Public Const LINEADDRESSTYPE_PHONENUMBER As Integer = &H1

    Sub Main()
        'initialize
        Dim gobjTapi As TAPI = New TAPI
        gobjTapi.Initialize()

        'select address
        Dim gobjAddress As ITAddress
        Dim objCollAddress As ITCollection
        objCollAddress = gobjTapi.Addresses

        Dim bFound As Boolean
        bFound = False
        Dim objCtrAddress As ITAddress
        Dim objMediaSupport As ITMediaSupport
        Dim objAddressCapabilities As ITAddressCapabilities

        Dim index As Integer
        For indexAddr As Integer = 1 To objCollAddress.Count
            objCtrAddress = objCollAddress.Item(indexAddr)
            objMediaSupport = objCtrAddress
            objAddressCapabilities = objCtrAddress

            If objMediaSupport.QueryMediaType(TAPIMEDIATYPE_AUDIO) And objCtrAddress.ServiceProviderName = "CiscoTSP001.tsp" Then
                bFound = True
            End If

            If bFound = True Then
                index = indexAddr
                Exit For
            End If

            objAddressCapabilities = Nothing
            objMediaSupport = Nothing
            objCtrAddress = Nothing
        Next

        gobjAddress = objCollAddress.Item(index)

        'make a call
        Dim gobjCall As ITBasicCallControl
        gobjCall = gobjAddress.CreateCall("172015727", LINEADDRESSTYPE_PHONENUMBER, TAPIMEDIATYPE_AUDIO)

        'select the terminal

        Dim objTerminalSupport As ITTerminalSupport
        objTerminalSupport = objAddressCapabilities

        Dim objTerminal As ITTerminal
        objTerminal = objTerminalSupport.GetDefaultStaticTerminal(TAPIMEDIATYPE_AUDIO, TERMINAL_DIRECTION.TD_CAPTURE)

        objTerminal = Nothing

        Dim objStreamControl As ITStreamControl

        objStreamControl = gobjCall

        If Not (objStreamControl Is Nothing) Then

            Dim objITCollStreams As ITCollection
            objITCollStreams = objStreamControl.Streams

            Dim nIndex As Long, objCrtStream As ITStream
            For nIndex = 1 To objITCollStreams.Count
                objCrtStream = objITCollStreams.Item(nIndex)
                If objCrtStream.MediaType = TAPIMEDIATYPE_AUDIO Then
                    If objCrtStream.Direction = TERMINAL_DIRECTION.TD_CAPTURE Then
                        objCrtStream.SelectTerminal(objTerminal)
                    End If
                End If
                objCrtStream = Nothing
            Next

            objITCollStreams = Nothing
            objStreamControl = Nothing
        End If
        'end  select terminal

        gobjCall.Connect(False)

        Thread.Sleep(3000)
        gobjCall.Disconnect(DISCONNECT_CODE.DC_NORMAL)

        gobjTapi.Shutdown()

    End Sub

End Module