Here's a list of links to several public route servers that you can use to perform some tests from outside your network.
If clicking on one of this links brings you to an error page of the browser then you're using Internet Explorer 7 where by default the
telnet:// protocol prefix is disabled, here's a little Windows Registry file you can download (Right click -> Save As) and double-click to merge it in your computer.
After this, any link with
telnet:// will simply open using your computer's default telnet application.
IE7_Telnet.reg 