Ok, I know everyone loves SkyPe, but it really isn't for free. VoIP takes
bandwidth, which costs money.

SkyPe has changed, it now users the generic ports which are normally
opened for web browsing. They don't have specific servers they connect to
to find the "hubs" on the Internet. So, there is not specific URL
blocking you can do. Even if you shut off transparent proxy, the user can
still configure SkyPe to use the proxy server.

Has anyone else figured out a way to block it using packet-filtering?

If yes could you please share?

For those of you who don't know a PC doing a 30 minute VoIP call can use
about 30MB up and down during the call. Multiply that by the number of
people using it, and your bandwidth is being used up.

Thanks in advance.