If you have a firewall installed, and you wish to allow WAN users access, you will need to open it at least on the port you have configured the web server to listen on. The packet type is TCP
For XP® Users that have enabled the built in default firewall protection, you will need to open a TCP port for the network card you wish to run the Proxy Server on. This can be accomplished by opening control panel and opening the control for network connections. From here press the properties button and click the Advanced tab. At the bottom of this tab you will find an button called "Settings". Pressing the "Add" button presents the dialog box which will allow you to add a rule that will allow an entry for the Phone Server.