Check to see if phone is busy.

[UrinatinventuM]

Hi There,

I want to check if a phone (modem, ISDN) connected to my computer is available or not, so I can see if I can make a call or not.
It doesn't have to be connected to the internet, but it could also be that I am calling to another person with this device (now why would I do that? ).

Greetz,
Bart

PS: I tried it this way, but I heard this doesn't work with ISDN:

Public Function ModemBusy(iComPortNo As Integer) As Boolean

   Dim iFreeFile As Integer

On Error GoTo ErrorHandling

   iFreeFile = FreeFile()

   ' Open the communications port.
   Open "COM" & iComPortNo & ":" For Output As #iFreeFile
   ' Send attention (AT).
   Print #iFreeFile, "AT"
   ModemBusy = False

ExitGracefully:
On Error Resume Next

   ' Close the port.
   Close #iFreeFile

   Exit Function

ErrorHandling:
   ModemBusy = True
   Resume ExitGracefully

End Function