I get this question at work a fair bit.

The reason your Speedtouch isn't on the list at portforward.com is that it isn't a router, it's a modem.
Unfortunately, that also means it can't forward ports.

It also means that port management is done by software on your PC. It varies between computer, but it is likely <a href="http://www.practicallynetworked.com/sharing/ics/icsconfiguration.htm">ICS</a>, which is very common. Check out the link for help configuring it.

Note: Port mapping == port forwarding.

Note 2: Some modem interface utilities will change ICS or port control for you.