Dial the Net Automatically

Does your application need to connect to the Internet?

Most code snippets simply show you how to display a typical connection dialog box. This method has three basic flaws; it doesn't force a dial-up, often requires the name of the connection and doesn't let you know when a connection has been made.

Thankfully this code snippet solves all those problems by using Internet Explorer's own automatic dial-up settings.

If you double-click the Internet Options icon in the Control Panel, you'll notice the Connections tab hosts a list of possible dial-up connections.

This snippet utilises a couple of little-known API calls that can automatically dial-up and disconnect from the default connection in that list – just like Internet Explorer does if it needs to connect to the Net.

Note: If the 'Never Dial a Connection' option is selected, this code will not be able to connect. It does as Internet Explorer does, and Internet Explorer simply wouldn't connect if that option was selected.

It's worth noting that this code pauses until the connection is actually made - or not, as the case may be. And that's definitely a good thing.

A project demonstrating this code is available for download here.

Code

This code is designed to be placed inside a Form with a Command Button.

Private Declare Function InternetAutodial Lib "wininet.dll" _
(ByVal dwFlags As Long, ByVal dwReserved As Long) As Long

Private Const INTERNET_AUTODIAL_FORCE_ONLINE = 1
Private Const INTERNET_AUTODIAL_FORCE_UNATTENDED = 2

Private Declare Function InternetAutodialHangup Lib "wininet.dll" _
(ByVal dwReserved As Long) As Long

Private Sub Command1_Click()

'To prompt the user to connect to the Net

If InternetAutodial(INTERNET_AUTODIAL_FORCE_ONLINE, 0) Then
	MsgBox "You're Connected!", vbInformation
End If

'To automatically start dialling

If InternetAutodial(INTERNET_AUTODIAL_FORCE_UNATTENDED, 0) Then
	MsgBox "You're Connected!", vbInformation
End If

'To disconnect an automatically dialled connection

If InternetAutodialHangup(0) Then
   MsgBox "You're Disconnected!", vbInformation
End If

End Sub