To allow the RAS Dialup component to dial a VPN or Dialup connection without showing the Dial Popup Dialog you have to change options on the connection not to prompt for the connection details such as username, password and phone number. To do this right-click on the connection from the Network Connections and click on Properties. On the options tab uncheck the following options:

1. Prompt for name and password, certificate, etc.
2. Prompt for phone number (Dialup connections only)