Private Sub ActiveLine_CallStateChanged(ByVal sender As Object, ByVal e As _
  JulMar.Atapi.CallStateEventArgs) Handles ActiveLine.CallStateChanged
        Dim x As String
 
        If e.CallState = CallState.Connected Then
            Debug.WriteLine(e.CallState.ToString)
            Handle = ActiveCall.GetCommHandle 'ist als SafeFileHandle 
            ' deklariert!
            CommStream = New System.IO.FileStream(Handle, _
              IO.FileAccess.ReadWrite, 512, True)
 
            'Test
            '################
            Write(Chr(13))
            x = Read()
            Debug.WriteLine(x)
 
        Else
            Debug.WriteLine(e.CallState.ToString)
        End If
    End Sub
 
 Private Sub Write(ByVal Text As String)
        Dim sw As System.IO.StreamWriter
        sw = New System.IO.StreamWriter(CommStream)
        sw.WriteLine(Text)
        CommStream.Flush()
 End Sub
 
 Private Function Read() As String
        Dim sr As System.IO.StreamReader
        sr = New System.IO.StreamReader(CommStream)
        Return sr.ReadLine() 'Hier kommt der Fehler : Handle ist ungültig
 End Function

VB RULEZ !