Function DialNumber(PhoneNumber)
   Dim msg As String, MsgBoxType As Integer, MsgBoxTitle As String
   Dim RetVal As Long
   Dim sName As String
 
    sName = Hauptform.Data1.Recordset.Fields("Name") & ":" & _
      Hauptform.Data1.Recordset.Fields("Ansprechpartner")
   ' Send the telephone number to the modem.
 
   RetVal = tapiRequestMakeCall(sPrefix & PhoneNumber & sSuffix, "", sName, "")
 
    ' sPrefix und sSuffix werden in unserem programm eingestellt (soll ein 0 
    ' davor)
 
   If RetVal < 0 Then
      msg = "Unable to dial number " & PhoneNumber
      GoTo Err_DialNumber
   End If
 
   Exit Function
 
Err_DialNumber:            'This is not an On Error routine.
   msg = msg & vbCr & vbCr & _
      "Make sure no other devices are using the Com port"
   MsgBoxType = MB_ICONSTOP
   MsgBoxTitle = "Dial Number Error"
   MsgBox msg, MsgBoxType, MsgBoxTitle
 
End Function