To enable Internet Connection Sharing on-demand dialing

You must be logged on as an administrator or a member of the Administrators group in order to complete this procedure. If your computer is connected to a network, network policy settings might also prevent you from completing this procedure.

Open Network Connections.
Click the network connection on which Internet Connection Sharing (ICS) is enabled, and then, under Network Tasks, click Change settings of this connection.
On the Advanced tab, under Internet Connection Sharing, do one of the following:
To enable ICS on-demand dialing, select the Establish a dial-up connection whenever a computer on my network attempts to access the Internet check box.
To disable ICS on-demand dialing, clear the Establish a dial-up connection whenever a computer on my network attempts to access the Internet check box.
Notes

To open Network Connections, click Start, click Control Panel, click Network and Internet Connections, and then click Network Connections.
Establish a dial-up connection whenever a computer on my network attempts to access the Internet is enabled by default. Unless you clear the check box, clients can activate the shared Internet connection from their computers by starting their Internet browsers or mail programs.
For ICS on-demand dialing to work correctly for ICS clients, the connection must be an all user connection, with the credentials saved for all users.
The Establish a dial-up connection whenever a computer on my network attempts to access the Internet check box is independent of the Allow other network users to control or disable the shared Internet connection check box.
If the Establish a dial-up connection whenever a computer on my network attempts to access the Internet check box is selected, when the ICS host computer detects a client's outbound Internet traffic, it connects to the Internet using the shared Internet connection. However, unless the Allow other network users to control or disable the shared Internet connection check box is selected, the client is unable to control when the connection connects or disconnects.