The Bridge

Imports System.Runtime.InteropServices

Namespace NCT.IaxClientWrapper.supported
    Public Class NCT_IaxClientWrapper
        Public Class NctIaxcEventArgsClass
            Inherits System.EventArgs
            Public eventType As NCT_IaxClientWrapper.EventTypes
            Public iaxcEvent As Object
            Public Sub New(ByVal e As Object, ByRef o As Object)
                eventType = e
                iaxcEvent = o
            End Sub
        End Class
        Public Event IAXClientEvent(ByVal sender As Object, ByVal evt As NctIaxcEventArgsClass)
        Public Function getCallInfo(ByVal callNo As Integer) As callInfo
            If callNo <= UBound(calls) And callNo >= LBound(calls) Then
                Return calls(callNo)
            Else
                Return (New callInfo)
            End If
        End Function
        Public Function getCurrentInputLevel() As Single
            Return CurrentInputLevel
        End Function
        Public Function getCurrentOutputLevel() As Single
            Return CurrentOutputLevel
        End Function
        Public Class callInfo
            Public numberptr As IntPtr = Marshal.AllocHGlobal(4)
            Public number As String
            Public callno As Integer
            Public callstatus As CallStates
            Public mediaformat As MediaFormats
            Public remote As String
            Public remoteName As String
            Public local As String
            Public localContext As String
            Public videoFormat As Integer
            Public videoWidth As Integer
            Public videoHeight As Integer
            Public videoUnsafeAddrPtr As Integer
            Public netstat_rtt As Integer
            Public LocalNetstats As iaxc_netstat
            Public RemoteNetstats As iaxc_netstat
            Public url As String
            Public urlType As UrlReplyTypes
            Public Sub setnumber(ByVal n As String)
                number = n
                numberptr = Marshal.StringToCoTaskMemAnsi(number)
            End Sub
            Protected Overrides Sub Finalize()
                Try
                    Marshal.FreeHGlobal(numberptr)
                Catch ex As Exception
                End Try
                MyBase.Finalize()
            End Sub
        End Class
        Public Function getIaxcVersion() As String
            Try
                Dim strptr As IntPtr = Marshal.AllocHGlobal(256)
                Dim version As String
                iaxc_version(strptr.ToInt32)
                version = Marshal.PtrToStringAnsi(strptr)
                Marshal.FreeHGlobal(strptr)
                Return version
            Catch ex As Exception
                Debug.WriteLine("Error trapped in iaxClientWrapper.version")
                Debug.WriteLine(ex.StackTrace)
            End Try
            Return ""
        End Function
        Public Sub setCallerId(ByVal name As String, ByVal number As String)
            Try
                calleridname = Marshal.StringToCoTaskMemAnsi(name)
                calleridnumber = Marshal.StringToCoTaskMemAnsi(number)
                iaxc_set_callerid(calleridname.ToInt32, calleridnumber.ToInt32)
            Catch ex As Exception
                Debug.WriteLine("Error trapped in iaxClientWrapper.setcallerid")
                Debug.WriteLine(ex.StackTrace)
            End Try
        End Sub
        Public Sub sendDTMF(ByVal digit As Char)
            Try
                iaxc_send_dtmf(digit)
            Catch ex As Exception
                Debug.WriteLine("Error trapped in iaxClientWrapper.sendtext")
                Debug.WriteLine(ex.StackTrace)
            End Try
        End Sub
        Public Sub sendText(ByVal text As String)
            Static textbin(50) As Object
            Static textbinnext As Integer
            Try
                Dim ptrobj As New pointerholder(text)
                textbin(textbinnext) = ptrobj
                textbinnext = textbinnext + 1
                If textbinnext > UBound(textbin) Then textbinnext = 0
                textbin(textbinnext) = Nothing
                iaxc_send_text(ptrobj.objectptr.ToInt32)
            Catch ex As Exception
                Debug.WriteLine("Error trapped in iaxClientWrapper.sendtext")
                Debug.WriteLine(ex.StackTrace)
            End Try
        End Sub
        Public Function stopSound(ByVal soundid As Integer) As Integer
            Try
                Dim n As Integer
                If ptrlist.ContainsKey("soundid:" + soundid.ToString) Then
                    ptrlist.Remove("soundid:" + soundid.ToString)
                End If
                n = iaxc_stop_sound(soundid)
                Return n
            Catch ex As Exception
                Debug.WriteLine("Error trapped in iaxClientWrapper.stopsound")
                Debug.WriteLine(ex.StackTrace)
            End Try
        End Function
        Public Function playSound(ByVal soundDef As iaxc_sound, Optional ByVal useRingOutputDevice As Boolean = False) As Integer
            Try
                Dim ptrobj As New pointerholder(soundDef)
                Dim n As Integer
                If useRingOutputDevice Then n = 1 Else n = 0
                n = iaxc_play_sound(ptrobj.objectptr.ToInt32, n)
                ptrlist.Add("soundid:" + n.ToString, ptrobj)
                Return n
            Catch ex As Exception
                Debug.WriteLine("Error trapped in iaxClientWrapper.playsound")
                Debug.WriteLine(ex.StackTrace)
            End Try
        End Function
        Public Function selectCall(ByVal number As String) As Integer
            If number <= UBound(calls) And number >= LBound(calls) Then
                Try
                    System.Threading.Monitor.Enter(calls(number))
                    Dim n As Integer
                    n = iaxc_select_call(number)
                    System.Threading.Monitor.Exit(calls(number))
                    Return n
                Catch ex As Exception
                    Debug.WriteLine("Error trapped in iaxClientWrapper.selectCall")
                    Debug.WriteLine(ex.StackTrace)
                End Try
            End If
        End Function
        Public Sub rejectCall(ByVal number As String)
            If number <= UBound(calls) And number >= LBound(calls) Then
                Try
                    Dim n As Integer
                    System.Threading.Monitor.Enter(calls(number))
                    n = calls(number).callstatus
                    If Not (n And CallStates.IAXC_CALL_STATE_RINGING) > 0 Then
                        Debug.WriteLine("That line isn't ringing")
                        Return
                    Else
                        iaxc_reject_call_number(number)
                    End If
                    System.Threading.Monitor.Exit(calls(number))
                Catch ex As Exception
                    Debug.WriteLine("Error trapped in iaxClientWrapper.rejectCall")
                    Debug.WriteLine(ex.StackTrace)
                End Try
            End If
        End Sub
        Public Sub hangup(ByVal number As String)
            dropCall(number)
        End Sub
        Public Sub dropCall(ByVal number As String)
            If number <= UBound(calls) And number >= LBound(calls) Then
                Try
                    Dim n As Integer
                    System.Threading.Monitor.Enter(calls(number))
                    n = calls(number).callstatus
                    If Not (n And CallStates.IAXC_CALL_STATE_ACTIVE) > 0 Then
                        Debug.WriteLine("That line isn't active")
                        Return
                    Else
                        n = iaxc_select_call(number)
                        If n >= 0 Then
                            iaxc_dump_call()
                        End If
                    End If
                    System.Threading.Monitor.Exit(calls(number))
                Catch ex As Exception
                    Debug.WriteLine("Error trapped in iaxClientWrapper.DropCall")
                    Debug.WriteLine(ex.StackTrace)
                End Try
            End If
        End Sub
        Public Sub answerCall(ByVal number As String)
            If number <= UBound(calls) And number >= LBound(calls) Then
                Try
                    Dim n As Integer
                    System.Threading.Monitor.Enter(calls(number))
                    n = calls(number).callstatus
                    If Not (n And CallStates.IAXC_CALL_STATE_RINGING) > 0 Then
                        Debug.WriteLine("That line isn't ringing")
                        Return
                    Else
                        iaxc_answer_call(number)
                    End If
                    System.Threading.Monitor.Exit(calls(number))
                Catch ex As Exception
                    Debug.WriteLine("Error trapped in iaxClientWrapper.AnswerCall")
                    Debug.WriteLine(ex.StackTrace)
                End Try
            End If
        End Sub
        Public Function placeCall(ByVal number As String) As Integer
            System.Threading.Monitor.Enter(calls)
            Dim callnumber As Integer
            Dim n As Integer = 0
            Try
                callnumber = iaxc_first_free_call()
                If callnumber < 0 Then
                    Debug.WriteLine("No available call lines.")
                    Return -1
                End If
                n = iaxc_select_call(callnumber)
                If n < 0 Then
                    Debug.WriteLine("Unable to select free call")
                    Return -1
                End If
                calls(callnumber).setnumber(number)
                iaxc_call(calls(callnumber).numberptr.ToInt32)
                System.Threading.Monitor.Exit(calls)
                Return callnumber
            Catch ex As Exception
                Debug.WriteLine("Error trapped in iaxClientWrapper.callout")
                Debug.WriteLine(ex.StackTrace)
            End Try
        End Function
        Public Function initialize(ByVal connectiontype As AudioTypes, ByVal MaxConcurrentCalls As Integer) As Boolean
            Dim t As String = "This application was created using the NCT IaxClientWrapper library.  " + _
                               "The library was" + Chr(13) + Chr(10) + "created by Andrew Pollack of Northern Collaborative Technologies " + _
                               "and may be used and" + Chr(13) + Chr(10) + "distributed subject to the following requirements: " + Chr(13) + Chr(10) _
                                       + Chr(13) + Chr(10) + _
                                       "1.  No money can be charged for any product of service which derives from this library. " _
                                       + Chr(13) + Chr(10) + Chr(13) + Chr(10) + _
                                       "2.  This message may not be removed, and must be displayed each time the library is used." _
                                       + Chr(13) + Chr(10) + Chr(13) + Chr(10) + _
                                       "3.  No attempt to reverse engineer or distribute any part of this library may be made." _
                                       + Chr(13) + Chr(10) + Chr(13) + Chr(10) + _
                                       "4.  The library is used at your own risk." _
                                       + Chr(13) + Chr(10) + Chr(13) + Chr(10) + Chr(13) + Chr(10) + _
                                       "If you would like to use this library in any other way, contact andrewp@thenorth.com" _
                                       + Chr(13) + Chr(10) + Chr(13) + Chr(10) + Chr(13) + Chr(10) + _
                                       "This library has been tested with build 566 of the IaxClientLibrary 'iaxclient.dll'.  Visit " + Chr(13) + Chr(10) + _
                                        "http://sourceforge.net/projects/iaxclient to find and build the latest version."
            'MsgBox(t, MsgBoxStyle.SystemModal, "NCT IaxClientWrapper")
            Dim n As Integer
            Try
                If Not clientInitialized Then
                    ' initialize the call holders
                    Dim localcalls(MaxConcurrentCalls - 1) As callInfo
                    For n = 0 To UBound(localcalls)
                        localcalls(n) = New callInfo
                    Next
                    calls = localcalls

                    ' make sure we have captured the handle first
                    If Me.captureEventHandle Then
                        ' initialize with the given parameters
                        n = iaxc_initialize(connectiontype, MaxConcurrentCalls)
                        If Not n = 0 Then
                            Debug.WriteLine("Failed to intitialize IAX Client: " + n.ToString)
                            Return False
                        End If
                        ' set up the event processing
                        n = iaxc_set_event_callpost(newprocptr, myeventid)
                        If Not n = 0 Then
                            Debug.WriteLine("Failed to setup event post routine: " + n.ToString)
                            Return False
                        End If
                        ' start the processing thread
                        n = iaxc_start_processing_thread()
                        If Not n = 0 Then
                            Debug.WriteLine("Failed to start the processing thread: " + n.ToString)
                            Return False
                        End If
                        clientInitialized = True
                        Return True
                    Else
                        Debug.WriteLine("Failed to capture events.  Exiting.")
                        Return False
                    End If
                Else
                    Debug.WriteLine("Client is already initialized")
                    Return True
                End If
            Catch ex As Exception
                Debug.WriteLine("Error trapped in iaxClientWrapper.initialize")
                Debug.WriteLine(ex.StackTrace)
                Return clientInitialized
            End Try
        End Function
        Public Function unregister(ByVal regid As Integer) As Boolean
            Dim n As Integer
            Try
                n = iaxc_unregister(regid)
                If Not n > 0 Then
                    Debug.WriteLine("Failed to unregister id: " + regid.ToString + " [" + n.ToString + "]")
                    Return False
                Else
                    Return True
                End If
            Catch ex As Exception
            End Try
        End Function
        Public Function register(ByVal username As String, ByVal password As String, ByVal hostaddr As String) As Integer
            Dim n As Integer
            Dim regContainer As regUserInfo
            Try
                Dim regidkey As String = username + "::" + hostaddr
                If reglist.ContainsKey(regidkey) Then
                    Debug.WriteLine("Removing existing registration first.")
                    regContainer = reglist.Item(regidkey)
                    unregister(regContainer.regid)
                Else
                    regContainer = Nothing
                End If
                If regContainer Is Nothing Then
                    regContainer = New regUserInfo(username, password, hostaddr)
                    reglist.Add(regidkey, regContainer)
                End If
                n = iaxc_register(regContainer.usernameptr.ToInt32, regContainer.passwordptr.ToInt32, regContainer.serveraddrptr.ToInt32)
                regContainer.regid = n
                If reglist.ContainsKey(regContainer.regid.ToString) Then
                    reglist.Remove(regContainer.regid.ToString)
                End If
                reglist.Add(regContainer.regid.ToString, regContainer)
                Return n
            Catch ex As Exception
                Debug.WriteLine("Error trapped in iaxClientWrapper.register")
                Debug.WriteLine(ex.StackTrace)
                Return clientInitialized
            End Try
        End Function
        Private CurrentInputLevel As Single
        Private CurrentOutputLevel As Single
        Private Shared calleridname As IntPtr = Marshal.AllocHGlobal(4)
        Private Shared calleridnumber As IntPtr = Marshal.AllocHGlobal(4)
        Private Shared delegateHandle As GCHandle
        Private Shared originalHandle As GCHandle
        Private nwin As System.Windows.Forms.NativeWindow
        Private Shared prevprocptr As Integer
        Private Shared newprocptr As Integer
        Private Shared myeventid As Integer
        Private Shared thisdelegate As SubClassProcDelegate
        Private Shared clientInitialized As Boolean = False
        Private Shared eventHandleCaptured As Boolean = False
        Private Shared reglist As Hashtable = New Hashtable
        Private Shared ptrlist As Hashtable = New Hashtable
        Private Shared calls() As callInfo

        ' The private classes for reguserinfo and pointerholder are used
        ' make sure that the required allocation of unmanaged memory is
        ' released any time of the object instances of them is destroyed
        ' by doing this in 'finalize()' we don't have to worry about it.
        Public Class regUserInfo
            Public usernameptr As IntPtr = Marshal.AllocHGlobal(4)
            Public passwordptr As IntPtr = Marshal.AllocHGlobal(4)
            Public serveraddrptr As IntPtr = Marshal.AllocHGlobal(4)
            Public regid As Integer = 0
            Public lastReply As Integer = 0
            Public Sub New(ByVal username As String, ByVal password As String, ByVal serveraddr As String)
                usernameptr = Marshal.StringToCoTaskMemAnsi(username)
                passwordptr = Marshal.StringToCoTaskMemAnsi(password)
                serveraddrptr = Marshal.StringToCoTaskMemAnsi(serveraddr)
            End Sub
            Protected Overrides Sub Finalize()
                Try
                    Marshal.FreeHGlobal(usernameptr)
                    Marshal.FreeHGlobal(passwordptr)
                    Marshal.FreeHGlobal(serveraddrptr)
                Catch ex As Exception
                End Try
                MyBase.Finalize()
            End Sub
        End Class
        Private Class pointerholder
            Public objectptr As IntPtr
            Public obj As Object
            Public Sub New(ByVal o As Object)
                objectptr = Marshal.AllocHGlobal(Marshal.SizeOf(o))
                obj = o
                Marshal.StructureToPtr(o, objectptr, True)
            End Sub
            Protected Overrides Sub finalize()
                Try
                    Marshal.FreeHGlobal(objectptr)
                Catch ex As Exception
                End Try
            End Sub
        End Class

#Region "IAXC Event Handlers - Internal to Class"
        ' CaptureEventHandle is called during initialize to make sure we get
        ' the event notifications from the dll
        Private Function captureEventHandle() As Boolean
            Try
                If Not eventHandleCaptured Then
                    Dim cp As New System.Windows.Forms.CreateParams
                    cp.Caption = "NCT Internal Event Window"
                    cp.Style = cp.Style And (Not &H10000000)
                    nwin = New System.Windows.Forms.NativeWindow
                    nwin.CreateHandle(cp)
                    Randomize()
                    myeventid = Int(Rnd() * 10000) + 60000
                    thisdelegate = AddressOf Me.handler
                    '   originalHandle = GCHandle.Alloc(Me.myinternalcontrol.Handle, GCHandleType.Pinned)
                    originalHandle = GCHandle.Alloc(Me.nwin.Handle, GCHandleType.Pinned)
                    ' newprocptr = Me.myinternalcontrol.Handle.ToInt32
                    newprocptr = Me.nwin.Handle.ToInt32
                    delegateHandle = GCHandle.Alloc(thisdelegate)
                    prevprocptr = SetWindowLong(newprocptr, -4, thisdelegate)
                    eventHandleCaptured = True
                Else
                    Debug.WriteLine("Event handle already captured")
                End If
            Catch ex As Exception
                eventHandleCaptured = False
                Debug.WriteLine("Error capturing event handle")
                Debug.WriteLine(ex.StackTrace)
            End Try
            Return eventHandleCaptured
        End Function
        ' handler() is method that actually receives the native window messages
        ' and dispatches the ones we want to deal with to processevent()
        Private Function handler(ByVal hwnd As Integer, ByVal msg As Integer, ByVal wParam As Integer, ByVal lParam As Integer) As Integer
            If msg = myeventid Then
                processEvent(lParam)
                Call iaxc_free_event(lParam)
                Return 1
            Else
                Return callwindowproc(prevprocptr, hwnd, msg, wParam, lParam)
            End If
        End Function
        ' processevent() recieves the event as an undefined object type and
        ' determines what kind of event it is.  Once determined, the object is cast
        ' to the correct event type and read from unmanaged memory, then dispatched
        ' to one of the overloaded processevent() types below
        Private Function processEvent(ByVal srcPtr As Integer) As Object
            Dim ptr As IntPtr = New IntPtr(srcPtr)
            ' ** we don't have to worry about nextevt because we are 
            ' using the post via OS method -- they all get to us in time
            Dim nextevt As Integer = Marshal.ReadInt32(ptr, 0)
            Dim type As Integer = Marshal.ReadInt32(ptr, 4)
            Dim localeventcopy As NctIaxcEventArgsClass
            Select Case type
                Case 1 ' text
                    Dim o As iaxc_ev_text = _
                        (CType(Marshal.PtrToStructure _
                        (ptr, GetType(iaxc_ev_text)), iaxc_ev_text))
                    localeventcopy = New NctIaxcEventArgsClass(type, CType(o, Object))
                    processEvent(o)
                    RaiseEvent IAXClientEvent(Me, localeventcopy)

                Case 2 ' Levels
                    Dim o As iaxc_ev_levels = _
                        (CType(Marshal.PtrToStructure( _
                        ptr, GetType(iaxc_ev_levels)), iaxc_ev_levels))
                    localeventcopy = New NctIaxcEventArgsClass(type, CType(o, Object))
                    processEvent(o)
                    RaiseEvent IAXClientEvent(Me, localeventcopy)
                Case 3 ' State
                    Dim o As iaxc_ev_call_state = _
                        (CType(Marshal.PtrToStructure( _
                        ptr, GetType(iaxc_ev_call_state)), iaxc_ev_call_state))
                    localeventcopy = New NctIaxcEventArgsClass(type, CType(o, Object))
                    processEvent(o)
                    RaiseEvent IAXClientEvent(Me, localeventcopy)
                Case 4 ' Netstat
                    Dim o As iaxc_ev_netstats = _
                        (CType(Marshal.PtrToStructure( _
                        ptr, GetType(iaxc_ev_netstats)), iaxc_ev_netstats))
                    localeventcopy = New NctIaxcEventArgsClass(type, CType(o, Object))
                    processEvent(o)
                    RaiseEvent IAXClientEvent(Me, localeventcopy)
                Case 5 ' URL
                    Dim o As iaxc_ev_url = _
                        (CType(Marshal.PtrToStructure( _
                        ptr, GetType(iaxc_ev_url)), iaxc_ev_url))
                    localeventcopy = New NctIaxcEventArgsClass(type, CType(o, Object))
                    processEvent(o)
                    RaiseEvent IAXClientEvent(Me, localeventcopy)
                Case 6 ' Video
                    Dim o As iaxc_ev_video = _
                        (CType(Marshal.PtrToStructure( _
                        ptr, GetType(iaxc_ev_video)), iaxc_ev_video))
                    localeventcopy = New NctIaxcEventArgsClass(type, CType(o, Object))
                    processEvent(o)
                    RaiseEvent IAXClientEvent(Me, localeventcopy)
                Case 7 ' Registration
                    Dim o As iaxc_ev_registration = _
                        (CType(Marshal.PtrToStructure( _
                        ptr, GetType(iaxc_ev_registration)), iaxc_ev_registration))
                    localeventcopy = New NctIaxcEventArgsClass(type, CType(o, Object))
                    processEvent(o)
                    RaiseEvent IAXClientEvent(Me, localeventcopy)
            End Select
            Return 0
        End Function
        ' each of the processevent() overloads below handles a specific kind of
        ' event, updating things in this class as needed.
        Private Sub processevent(ByVal evt As iaxc_ev_text)
            'nothing is required
        End Sub

        Private Sub processevent(ByVal evt As iaxc_ev_levels)
            If Not ((CurrentInputLevel = evt.input) And (CurrentOutputLevel = evt.output)) Then
                CurrentInputLevel = evt.input
                CurrentOutputLevel = evt.output
            End If
        End Sub
        Private Sub processevent(ByVal evt As iaxc_ev_registration)
            If reglist.ContainsKey(evt.id.ToString) Then
                Dim userreg As regUserInfo = reglist.Item(evt.id.ToString)
                If Not userreg Is Nothing Then userreg.lastReply = evt.reply
            End If
        End Sub
        Private Sub processevent(ByVal evt As iaxc_ev_call_state)
            System.Threading.Monitor.Enter(calls)
            calls(evt.callno).callstatus = evt.state
            calls(evt.callno).mediaformat = evt.format
            calls(evt.callno).remote = evt.remote
            calls(evt.callno).remoteName = evt.remote_name
            calls(evt.callno).local = evt.local
            calls(evt.callno).localContext = evt.local_context
            If evt.state And CallStates.IAXC_CALL_STATE_FREE Then
                calls(evt.callno).videoFormat = 0
                calls(evt.callno).videoHeight = 0
                calls(evt.callno).videoWidth = 0
                calls(evt.callno).videoUnsafeAddrPtr = 0
                calls(evt.callno).url = ""
                calls(evt.callno).urlType = 0
                Dim ns As iaxc_netstat
                calls(evt.callno).RemoteNetstats = ns
                calls(evt.callno).LocalNetstats = ns
                calls(evt.callno).netstat_rtt = 0
            End If
            System.Threading.Monitor.Exit(calls)
        End Sub
        Private Sub processevent(ByVal evt As iaxc_ev_video)
            System.Threading.Monitor.Enter(calls)
            calls(evt.callno).videoFormat = evt.format
            calls(evt.callno).videoHeight = evt.height
            calls(evt.callno).videoWidth = evt.width
            calls(evt.callno).videoUnsafeAddrPtr = evt.datapointer
            System.Threading.Monitor.Exit(calls)
        End Sub
        Private Sub processevent(ByVal evt As iaxc_ev_netstats)
            System.Threading.Monitor.Enter(calls)
            calls(evt.callno).netstat_rtt = evt.rtt
            calls(evt.callno).LocalNetstats = evt.local
            calls(evt.callno).RemoteNetstats = evt.remote
            System.Threading.Monitor.Exit(calls)
        End Sub
        Private Sub processevent(ByVal evt As iaxc_ev_url)
            System.Threading.Monitor.Enter(calls)
            calls(evt.callno).url = evt.url
            calls(evt.callno).urlType = evt.urltype
            System.Threading.Monitor.Exit(calls)
        End Sub
#End Region

#Region "IAXC Enumerations"

        Enum MediaFormats As Integer
            IAXC_FORMAT_g723_1 = (1 << 0)
            IAXC_FORMAT_GSM = (1 << 1)
            IAXC_FORMAT_ULAW = (1 << 2)
            IAXC_FORMAT_ALAW = (1 << 3)
            IAXC_FORMAT_G726 = (1 << 4)
            IAXC_FORMAT_ADPCM = (1 << 5)
            IAXC_FORMAT_SLINEAR = (1 << 6)
            IAXC_FORMAT_LPC10 = (1 << 7)
            IAXC_FORMAT_G729A = (1 << 8)
            IAXC_FORMAT_SPEEX = (1 << 9)
            IAXC_FORMAT_ILBC = (1 << 10)
            IAXC_FORMAT_MAX_AUDIO = (1 << 15)
            IAXC_FORMAT_JPEG = (1 << 16)
            IAXC_FORMAT_PNG = (1 << 17)
            IAXC_FORMAT_H261 = (1 << 18)
            IAXC_FORMAT_H263 = (1 << 19)
            IAXC_FORMAT_H263_PLUS = (1 << 20)
            IAXC_FORMAT_MPEG4 = (1 << 21)
            IAXC_FORMAT_H264 = (1 << 23)
            IAXC_FORMAT_THEORA = (1 << 24)
        End Enum

        Enum AudioTypes As Integer
            AUDIO_INTERNAL_PA = 1
            AUDIO_INTERNAL_FILE_UNSUPPORTED = 2
            AUDIO_INTERNAL_ALSA_UNSUPPORTED = 3
            AUDIO_INTERNAL_PA_PRESETMIXER = 4
            AUDIO_EXTERNAL_UNSUPPORTED = 99
        End Enum

        Public Enum EventTypes
            IAXC_EVENT_TEXT = 1
            IAXC_EVENT_LEVELS = 2
            IAXC_EVENT_STATE = 3
            IAXC_EVENT_NETSTAT = 4
            IAXC_EVENT_URL = 5 ' URL push via IAX(2) 
            IAXC_EVENT_VIDEO = 6 ' video data (pointer) 
            IAXC_EVENT_REGISTRATION = 7
        End Enum

        Public Enum CallStates
            IAXC_CALL_STATE_FREE = 0
            IAXC_CALL_STATE_ACTIVE = (1 << 1)
            IAXC_CALL_STATE_OUTGOING = (1 << 2)
            IAXC_CALL_STATE_RINGING = (1 << 3)
            IAXC_CALL_STATE_COMPLETE = (1 << 4)
            IAXC_CALL_STATE_SELECTED = (1 << 5)
            IAXC_CALL_STATE_BUSY = (1 << 6)
            IAXC_CALL_STATE_TRANSFER = (1 << 7)
        End Enum

        Public Enum TextEventTypes
            IAXC_TEXT_TYPE_STATUS = 1
            IAXC_TEXT_TYPE_NOTICE = 2
            IAXC_TEXT_TYPE_ERROR = 3
            ' FATAL ERROR: User Agent should probably display error, then die. 
            IAXC_TEXT_TYPE_FATALERROR = 4
            IAXC_TEXT_TYPE_IAX = 5
        End Enum

        Public Enum RegistrationReplyTypes
            IAXC_REGISTRATION_REPLY_ACK = 18 ' IAX_EVENT_REGACC 
            IAXC_REGISTRATION_REPLY_REJ = 30 ' IAX_EVENT_REGREJ 
            IAXC_REGISTRATION_REPLY_TIMEOUT = 6 ' IAX_EVENT_TIMEOUT 
        End Enum

        Public Enum UrlReplyTypes
            IAXC_URL_URL = 1 ' URL received 
            IAXC_URL_LDCOMPLETE = 2 ' URL loading complete 
            IAXC_URL_LINKURL = 3 ' URL link request 
            IAXC_URL_LINKREJECT = 4 ' URL link reject 
            IAXC_URL_UNLINK = 5 ' URL unlink 
        End Enum

        'Friend Const IAXC_EVENT_BUFSIZ = 256

        Public Enum AudioDeviceTypes
            IAXC_AD_INPUT = (1 << 0)
            IAXC_AD_OUTPUT = (1 << 1)
            IAXC_AD_RING = (1 << 2)
            IAXC_AD_INPUT_DEFAULT = (1 << 3)
            IAXC_AD_OUTPUT_DEFAULT = (1 << 4)
            IAXC_AD_RING_DEFAULT = (1 << 5)
        End Enum

        Public Enum FilterTypes
            IAXC_FILTER_DENOISE = (1 << 0)
            IAXC_FILTER_AGC = (1 << 1)
            IAXC_FILTER_ECHO = (1 << 2)
            IAXC_FILTER_AAGC = (1 << 3) ' Analog (mixer-based) AGC 
            IAXC_FILTER_CN = (1 << 4) ' Send CN frames when silence detected 
        End Enum
#End Region
#Region "IAXC INTERNAL STRUCTURES"

        Public Structure iaxc_ev_levels
            Friend nextEvent As Integer
            Friend eventtype As Integer
            Public input As Single
            Public output As Single
        End Structure

        Public Structure iaxc_ev_text
            Friend nextEvent As Integer
            Friend eventtype As Integer
            Public type As Int32
            Public callno As Int32
            <MarshalAsAttribute(UnmanagedType.ByValTStr, sizeconst:=256)> Public text As String
        End Structure

        Public Structure iaxc_ev_call_state
            Friend nextEvent As Integer
            Friend eventtype As Integer
            Public callno As Int32
            Public state As Int32
            Public format As Int32
            <MarshalAsAttribute(UnmanagedType.ByValTStr, sizeconst:=256)> Public remote As String
            <MarshalAsAttribute(UnmanagedType.ByValTStr, sizeconst:=256)> Public remote_name As String
            <MarshalAsAttribute(UnmanagedType.ByValTStr, sizeconst:=256)> Public local As String
            <MarshalAsAttribute(UnmanagedType.ByValTStr, sizeconst:=256)> Public local_context As String
        End Structure

        Public Structure iaxc_netstat
            Public jitter As Int32
            Public losspct As Int32
            Public losscnt As Int32
            Public packets As Int32
            Public delay As Int32
            Public dropped As Int32
            Public ooo As Int32
        End Structure

        Public Structure iaxc_ev_netstats
            Friend nextEvent As Integer
            Friend eventtype As Integer
            Public callno As Int32
            Public rtt As Int32
            Public local As iaxc_netstat
            Public remote As iaxc_netstat
        End Structure

        Public Structure iaxc_ev_url
            Friend nextEvent As Integer
            Friend eventtype As Integer
            Public callno As Int32
            Public urltype As Int32
            <MarshalAsAttribute(UnmanagedType.ByValTStr, sizeconst:=256)> Public url As String
        End Structure

        Public Structure iaxc_ev_video
            Friend nextEvent As Integer
            Friend eventtype As Integer
            Public callno As Int32
            Public format As Int32
            Public width As Int32
            Public height As Int32
            Public datapointer As Long
        End Structure

        Public Structure iaxc_ev_registration
            Friend nextEvent As Integer
            Friend eventtype As Integer
            Public id As Int32
            Public reply As Int32
            Public msgcount As Int32
        End Structure

        Public Structure iaxc_audio_device
            Public devnameptrint As Integer
            Public caps As Int32
            Public devid As Integer
            Public name As String
        End Structure

        Public Structure iaxc_sound
            Public dataAddr As Int16
            Public length As Long
            Public malloced As Integer '/* should the library free() the data after being played? */
            Public channel As Integer  '/* 0 for outpub selected, 1 for ringselected */
            Public repeat As Integer '/* -1 for inifinite */
            Public position As Long '/* internal */
            Public id As Integer '/* internal */
            Public addrOfNextSound As Integer
        End Structure
#End Region


        ' The finalize event makes sure we de-allocate memory in a few places we 
        ' have allocated it in unmanaged resources
        Protected Overrides Sub finalize()
            Try
                If clientInitialized Then iaxc_shutdown()
            Catch ex As Exception
                Debug.WriteLine(ex.StackTrace)
            End Try
            Try
                delegateHandle.Free()
                originalHandle.Free()
                Marshal.FreeHGlobal(calleridname)
                Marshal.FreeHGlobal(calleridnumber)
            Catch ex As Exception
            End Try
            MyBase.Finalize()
        End Sub

        Private Sub NCT_IaxClientWrapper_IAXClientEvent(ByVal sender As Object, ByVal evt As NctIaxcEventArgsClass) Handles Me.IAXClientEvent

        End Sub
    End Class

    Module WinAPIcalls

        ' Resets the window handle used by the OS to pass event messages to our own handler
        Declare Function SetWindowLong Lib "USER32.DLL" Alias "SetWindowLongA" ( _
            ByVal hwnd As Integer, ByVal attr As Integer, _
            ByVal lVal As SubClassProcDelegate) As Integer

        ' Used to pass a message to another handler - we use this to call the native window
        ' handler for any events we get that we're not dealing with ourselves, since we have
        ' intercepted all the events and if we don't do this, they won't get handled.
        Declare Function callwindowproc Lib "user32.dll" Alias "CallWindowProcA" ( _
            ByVal prevprocptr As Integer, ByVal hwnd As Integer, _
            ByVal msg As Integer, ByVal wparam As Integer, ByVal lparam As Integer) As Integer

        ' Creates a delegate object to assign the address of a method with a match signature
        Delegate Function SubClassProcDelegate( _
            ByVal hwnd As Integer, ByVal msg As Integer, _
            ByVal wParam As Integer, ByVal lParam As Integer) As Integer

    End Module
    Module iaxc_function_calls
        Friend Declare Sub iaxc_answer_call Lib "iaxclient.dll" Alias "iaxc_answer_call" (ByVal callno As Integer)
        Friend Declare Function iaxc_audio_devices_get Lib "iaxclient.dll" Alias "iaxc_audio_devices_get" (ByVal devlistptrInt As Integer, ByVal ndevsptrInt As Integer, ByVal InputptrInt As Integer, ByVal OutputptrInt As Integer, ByVal ringptrInt As Integer) As Integer
        Friend Declare Sub iaxc_audio_devices_set Lib "iaxclient.dll" Alias "iaxc_audio_devices_set" (ByVal input As Integer, ByVal output As Integer, ByVal ring As Integer)
        Friend Declare Sub iaxc_blind_transfer_call Lib "iaxclient.dll" Alias "iaxc_blind_transfer_call" (ByVal callNo As Integer, ByVal number As Integer)
        Friend Declare Sub iaxc_call Lib "iaxclient.dll" Alias "iaxc_call" (ByVal callto As Integer)
        Friend Declare Sub iaxc_dump_all_calls Lib "iaxclient.dll" Alias "iaxc_dump_all_calls" ()
        Friend Declare Sub iaxc_dump_call Lib "iaxclient.dll" Alias "iaxc_dump_call" ()
        Friend Declare Function iaxc_first_free_call Lib "iaxclient.dll" Alias "iaxc_first_free_call" () As Integer
        Friend Declare Sub iaxc_free_event Lib "iaxclient.dll" Alias "iaxc_free_event" (ByVal eventHandle As Integer)
        Friend Declare Function iaxc_get_event_levels Lib "iaxclient.dll" Alias "iaxc_get_event_levels" (ByVal evtAddr As Integer) As Integer
        Friend Declare Function iaxc_get_event_state Lib "iaxclient.dll" Alias "iaxc_get_event_state" (ByVal evtAddr As Integer) As Integer
        Friend Declare Function iaxc_get_event_text Lib "iaxclient.dll" Alias "iaxc_get_event_text" (ByVal evtAddr As Integer) As Integer
        Friend Declare Function iaxc_get_filters Lib "iaxclient.dll" Alias "iaxc_get_filters" () As Integer
        Friend Declare Function iaxc_get_netstats Lib "iaxclient.dll" Alias "iaxc_get_netstats" (ByVal callno As Integer, ByVal addrOfRTT As Integer, ByVal netStatAddrLocal As Integer, ByVal netStatAddrRemote As Integer) As Integer
        Friend Declare Function iaxc_initialize Lib "iaxclient.dll" Alias "iaxc_initialize" (ByVal audtype As Int32, ByVal ncalls As Int32) As Int32
        Friend Declare Function iaxc_input_level_get Lib "iaxclient.dll" Alias "iaxc_input_level_get" () As Double
        Friend Declare Function iaxc_input_level_set Lib "iaxclient.dll" Alias "iaxc_input_level_set" (ByVal level As Double) As Integer
        Friend Declare Sub iaxc_keep_default_input_line Lib "iaxclient.dll" Alias "iaxc_keep_default_input_line" (ByVal OneEqualsTrue As Integer)
        Friend Declare Function iaxc_mic_boost_get Lib "iaxclient.dll" Alias "iaxc_mic_boost_get" () As Integer
        Friend Declare Function iaxc_mic_boost_set Lib "iaxclient.dll" Alias "iaxc_mic_boost_set" (ByVal level As Integer) As Integer
        Friend Declare Sub iaxc_millisleep Lib "iaxclient.dll" Alias "iaxc_millisleep" (ByVal milliseconds As Long)
        Friend Declare Function iaxc_output_level_get Lib "iaxclient.dll" Alias "iaxc_output_level_get" () As Double
        Friend Declare Function iaxc_output_level_set Lib "iaxclient.dll" Alias "iaxc_output_level_set" (ByVal level As Double) As Integer
        Friend Declare Function iaxc_play_sound Lib "iaxclient.dll" Alias "iaxc_play_sound" (ByVal soundStructAddr As Integer, ByVal outdevice As Integer) As Integer
        Friend Declare Sub iaxc_process_calls Lib "iaxclient.dll" Alias "iaxc_process_calls" ()
        Friend Declare Function iaxc_quelch Lib "iaxclient.dll" Alias "iaxc_quelch" (ByVal callno As Integer) As Integer
        Friend Declare Function iaxc_register Lib "iaxclient.dll" Alias "iaxc_register" (ByVal user As Integer, ByVal pass As Integer, ByVal host As Integer) As Int32
        Friend Declare Sub iaxc_reject_call Lib "iaxclient.dll" Alias "iaxc_reject_call" ()
        Friend Declare Sub iaxc_reject_call_number Lib "iaxclient.dll" Alias "iaxc_reject_call_number" (ByVal callno As Integer)
        Friend Declare Function iaxc_select_call Lib "iaxclient.dll" Alias "iaxc_select_call" (ByVal callno As Integer) As Integer
        Friend Declare Function iaxc_selected_call Lib "iaxclient.dll" Alias "iaxc_selected_call" () As Integer
        Friend Declare Sub iaxc_send_dtmf Lib "iaxclient.dll" Alias "iaxc_send_dtmf" (ByVal digit As Char)
        Friend Declare Sub iaxc_send_text Lib "iaxclient.dll" Alias "iaxc_send_text" (ByVal textAddr As Integer)
        Friend Declare Sub iaxc_send_url Lib "iaxclient.dll" Alias "iaxc_send_url" (ByVal urlAddr As Integer, ByVal link As Integer)
        Friend Declare Sub iaxc_set_audio_output Lib "iaxclient.dll" Alias "iaxc_set_audio_output" (ByVal output As Int32)
        Friend Declare Sub iaxc_set_callerid Lib "iaxclient.dll" Alias "iaxc_set_callerid" (ByVal nameAddr As Integer, ByVal numberAddr As Integer)
        Friend Declare Sub iaxc_set_event_callback Lib "iaxclient.dll" Alias "iaxc_set_event_callback" (ByVal callBackDelegateAddr As Int32)
        Friend Declare Function iaxc_set_event_callpost Lib "iaxclient.dll" Alias "iaxc_set_event_callpost" (ByVal hwnd As Integer, ByVal id As Integer) As Integer
        Friend Declare Function iaxc_set_files Lib "iaxclient.dll" Alias "iaxc_set_files" (ByVal inputFileAddr As Integer, ByVal outputFileAddr As Integer) As Integer
        Friend Declare Sub iaxc_set_filters Lib "iaxclient.dll" Alias "iaxc_set_filters" (ByVal filters As Integer)
        Friend Declare Sub iaxc_set_formats Lib "iaxclient.dll" Alias "iaxc_set_formats" (ByVal preferred As Int32, ByVal allows As Int32)
        Friend Declare Sub iaxc_set_min_outgoing_framesize Lib "iaxclient.dll" Alias "iaxc_set_min_outgoing_framesize" (ByVal samples As Integer)
        Friend Declare Sub iaxc_set_networking Lib "iaxclient.dll" Alias "iaxc_set_networking" (ByVal sendToFunctionDelegateAddr As Integer, ByVal recvFromFunctionDelegateAddr As Integer)
        Friend Declare Sub iaxc_set_preferred_source_udp_port Lib "iaxclient.dll" Alias "iaxc_set_preferred_source_udp_port" (ByVal udpPort As Integer)
        Friend Declare Sub iaxc_set_silence_threshold Lib "iaxclient.dll" Alias "iaxc_set_silence_threshold" (ByVal val As Double)
        Friend Declare Sub iaxc_set_speex_settings Lib "iaxclient.dll" Alias "iaxc_set_speex_settings" (ByVal decodeEnhance As Integer, ByVal quality As Single, ByVal bitrate As Integer, ByVal vbr As Integer, ByVal abr As Integer, ByVal complexity As Integer)
        Friend Declare Sub iaxc_shutdown Lib "iaxclient.dll" Alias "iaxc_shutdown" ()
        Friend Declare Function iaxc_start_processing_thread Lib "iaxclient.dll" Alias "iaxc_start_processing_thread" () As Int32
        Friend Declare Function iaxc_stop_processing_thread Lib "iaxclient.dll" Alias "iaxc_stop_processing_thread" () As Integer
        Friend Declare Function iaxc_stop_sound Lib "iaxclient.dll" Alias "iaxc_stop_sound" (ByVal id As Integer) As Integer
        Friend Declare Function iaxc_unquelch Lib "iaxclient.dll" Alias "iaxc_unquelch" (ByVal callno As Integer) As Integer
        Friend Declare Function iaxc_unregister Lib "iaxclient.dll" Alias "iaxc_unregister" (ByVal id As Integer) As Integer
        Friend Declare Function iaxc_version Lib "iaxclient.dll" Alias "iaxc_version" (ByVal versionStringAddr As Integer) As Integer
    End Module
End Namespace
Namespace NCT.IaxClientWrapper.Unsupported
    Public Module iaxc_function_calls
        Public Declare Sub iaxc_answer_call Lib "iaxclient.dll" Alias "iaxc_answer_call" (ByVal callno As Integer)
        'Public Declare Function iaxc_audio_devices_get Lib "iaxclient.dll" Alias "iaxc_audio_devices_get" (ByVal devlistptrInt As Integer, ByVal ndevsptrInt As Integer, ByVal InputptrInt As Integer, ByVal OutputptrInt As Integer, ByVal ringptrInt As Integer) As Integer
        Public Declare Function iaxc_audio_devices_get Lib "iaxclient.dll" Alias "iaxc_audio_devices_get" (ByRef devlistptrInt As IntPtr, ByRef ndevsptrInt As Integer, ByRef InputptrInt As Integer, ByRef OutputptrInt As Integer, ByRef ringptrInt As Integer) As Integer
        Public Declare Sub iaxc_audio_devices_set Lib "iaxclient.dll" Alias "iaxc_audio_devices_set" (ByVal input As Integer, ByVal output As Integer, ByVal ring As Integer)
        Public Declare Sub iaxc_blind_transfer_call Lib "iaxclient.dll" Alias "iaxc_blind_transfer_call" (ByVal callNo As Integer, ByVal number As Integer)
        Public Declare Sub iaxc_call Lib "iaxclient.dll" Alias "iaxc_call" (ByVal callto As Integer)
        Public Declare Sub iaxc_dump_all_calls Lib "iaxclient.dll" Alias "iaxc_dump_all_calls" ()
        Public Declare Sub iaxc_dump_call Lib "iaxclient.dll" Alias "iaxc_dump_call" ()
        Public Declare Sub iaxc_first_free_call Lib "iaxclient.dll" Alias "iaxc_first_free_call" ()
        Public Declare Sub iaxc_free_event Lib "iaxclient.dll" Alias "iaxc_free_event" (ByVal eventHandle As Integer)
        Public Declare Function iaxc_get_event_levels Lib "iaxclient.dll" Alias "iaxc_get_event_levels" (ByVal evtAddr As Integer) As Integer
        Public Declare Function iaxc_get_event_state Lib "iaxclient.dll" Alias "iaxc_get_event_state" (ByVal evtAddr As Integer) As Integer
        Public Declare Function iaxc_get_event_text Lib "iaxclient.dll" Alias "iaxc_get_event_text" (ByVal evtAddr As Integer) As Integer
        Public Declare Function iaxc_get_filters Lib "iaxclient.dll" Alias "iaxc_get_filters" () As Integer
        Public Declare Function iaxc_get_netstats Lib "iaxclient.dll" Alias "iaxc_get_netstats" (ByVal callno As Integer, ByVal addrOfRTT As Integer, ByVal netStatAddrLocal As Integer, ByVal netStatAddrRemote As Integer) As Integer
        Public Declare Function iaxc_initialize Lib "iaxclient.dll" Alias "iaxc_initialize" (ByVal audtype As Int32, ByVal ncalls As Int32) As Int32
        Public Declare Function iaxc_input_level_get Lib "iaxclient.dll" Alias "iaxc_input_level_get" () As Double
        Public Declare Function iaxc_input_level_set Lib "iaxclient.dll" Alias "iaxc_input_level_set" (ByVal level As Double) As Integer
        Public Declare Sub iaxc_keep_default_input_line Lib "iaxclient.dll" Alias "iaxc_keep_default_input_line" (ByVal OneEqualsTrue As Integer)
        Public Declare Function iaxc_mic_boost_get Lib "iaxclient.dll" Alias "iaxc_mic_boost_get" () As Integer
        Public Declare Function iaxc_mic_boost_set Lib "iaxclient.dll" Alias "iaxc_mic_boost_set" (ByVal level As Integer) As Integer
        Public Declare Sub iaxc_millisleep Lib "iaxclient.dll" Alias "iaxc_millisleep" (ByVal milliseconds As Long)
        Public Declare Function iaxc_output_level_get Lib "iaxclient.dll" Alias "iaxc_output_level_get" () As Double
        Public Declare Function iaxc_output_level_set Lib "iaxclient.dll" Alias "iaxc_output_level_set" (ByVal level As Double) As Integer
        Public Declare Function iaxc_play_sound Lib "iaxclient.dll" Alias "iaxc_play_sound" (ByVal soundStructAddr As Integer, ByVal outdevice As Integer) As Integer
        Public Declare Sub iaxc_process_calls Lib "iaxclient.dll" Alias "iaxc_process_calls" ()
        Public Declare Function iaxc_quelch Lib "iaxclient.dll" Alias "iaxc_quelch" (ByVal callno As Integer) As Integer
        Public Declare Function iaxc_register Lib "iaxclient.dll" Alias "iaxc_register" (ByVal user As Integer, ByVal pass As Integer, ByVal host As Integer) As Int32
        Public Declare Sub iaxc_reject_call Lib "iaxclient.dll" Alias "iaxc_reject_call" ()
        Public Declare Sub iaxc_reject_call_number Lib "iaxclient.dll" Alias "iaxc_reject_call_number" (ByVal callno As Integer)
        Public Declare Function iaxc_select_call Lib "iaxclient.dll" Alias "iaxc_select_call" (ByVal callno As Integer) As Integer
        Public Declare Function iaxc_selected_call Lib "iaxclient.dll" Alias "iaxc_selected_call" () As Integer
        Public Declare Sub iaxc_send_dtmf Lib "iaxclient.dll" Alias "iaxc_send_dtmf" (ByVal digit As Char)
        Public Declare Sub iaxc_send_text Lib "iaxclient.dll" Alias "iaxc_send_text" (ByVal textAddr As Integer)
        Public Declare Sub iaxc_send_url Lib "iaxclient.dll" Alias "iaxc_send_url" (ByVal urlAddr As Integer, ByVal link As Integer)
        Public Declare Sub iaxc_set_audio_output Lib "iaxclient.dll" Alias "iaxc_set_audio_output" (ByVal output As Int32)
        Public Declare Sub iaxc_set_callerid Lib "iaxclient.dll" Alias "iaxc_set_callerid" (ByVal nameAddr As Integer, ByVal numberAddr As Integer)
        Public Declare Sub iaxc_set_event_callback Lib "iaxclient.dll" Alias "iaxc_set_event_callback" (ByVal callBackDelegateAddr As Int32)
        Public Declare Function iaxc_set_event_callpost Lib "iaxclient.dll" Alias "iaxc_set_event_callpost" (ByVal hwnd As Integer, ByVal id As Integer) As Integer
        Public Declare Function iaxc_set_files Lib "iaxclient.dll" Alias "iaxc_set_files" (ByVal inputFileAddr As Integer, ByVal outputFileAddr As Integer) As Integer
        Public Declare Sub iaxc_set_filters Lib "iaxclient.dll" Alias "iaxc_set_filters" (ByVal filters As Integer)
        Public Declare Sub iaxc_set_formats Lib "iaxclient.dll" Alias "iaxc_set_formats" (ByVal preferred As Int32, ByVal allows As Int32)
        Public Declare Sub iaxc_set_min_outgoing_framesize Lib "iaxclient.dll" Alias "iaxc_set_min_outgoing_framesize" (ByVal samples As Integer)
        Public Declare Sub iaxc_set_networking Lib "iaxclient.dll" Alias "iaxc_set_networking" (ByVal sendToFunctionDelegateAddr As Integer, ByVal recvFromFunctionDelegateAddr As Integer)
        Public Declare Sub iaxc_set_preferred_source_udp_port Lib "iaxclient.dll" Alias "iaxc_set_preferred_source_udp_port" (ByVal udpPort As Integer)
        Public Declare Sub iaxc_set_silence_threshold Lib "iaxclient.dll" Alias "iaxc_set_silence_threshold" (ByVal val As Double)
        Public Declare Sub iaxc_set_speex_settings Lib "iaxclient.dll" Alias "iaxc_set_speex_settings" (ByVal decodeEnhance As Integer, ByVal quality As Single, ByVal bitrate As Integer, ByVal vbr As Integer, ByVal abr As Integer, ByVal complexity As Integer)
        Public Declare Sub iaxc_shutdown Lib "iaxclient.dll" Alias "iaxc_shutdown" ()
        Public Declare Function iaxc_start_processing_thread Lib "iaxclient.dll" Alias "iaxc_start_processing_thread" () As Int32
        Public Declare Function iaxc_stop_processing_thread Lib "iaxclient.dll" Alias "iaxc_stop_processing_thread" () As Integer
        Public Declare Function iaxc_stop_sound Lib "iaxclient.dll" Alias "iaxc_stop_sound" (ByVal id As Integer) As Integer
        Public Declare Function iaxc_unquelch Lib "iaxclient.dll" Alias "iaxc_unquelch" (ByVal callno As Integer) As Integer
        Public Declare Function iaxc_unregister Lib "iaxclient.dll" Alias "iaxc_unregister" (ByVal id As Integer) As Integer
        Public Declare Function iaxc_version Lib "iaxclient.dll" Alias "iaxc_version" (ByVal versionStringAddr As Integer) As Integer
        Function GetAudio() As Collection
            Dim retDevices As New Collection
            Dim ptrDevices As IntPtr = IntPtr.Zero
            Dim nDevs As Integer = 0
            Dim input As Integer = 0
            Dim output As Integer = 0
            Dim ring As Integer = 0

            iaxc_audio_devices_get(ptrDevices, nDevs, input, output, ring)
            If nDevs > 0 Then
                Dim current As IntPtr = ptrDevices
                Dim device As supported.NCT_IaxClientWrapper.iaxc_audio_device

                Dim i As Integer = 0
                For i = 0 To nDevs - 2
                    device = CType(Marshal.PtrToStructure(current, GetType(supported.NCT_IaxClientWrapper.iaxc_audio_device)), supported.NCT_IaxClientWrapper.iaxc_audio_device)
                    retDevices.Add(device)

                    Marshal.DestroyStructure(current, GetType(supported.NCT_IaxClientWrapper.iaxc_audio_device))
                    'current = CType((CType(current, Integer) + Marshal.SizeOf(device)), IntPtr)
                    current = CType((CType(current, Integer) + 12), IntPtr)

                    'System.Math.Min(System.Threading.Interlocked.Increment(i), i - 1)
                    Console.Write(device.name & vbCrLf)
                    device = Nothing
                Next
                Marshal.FreeCoTaskMem(ptrDevices)
            End If

            Return retDevices
        End Function

    End Module

End Namespace