Hi
Port Forwarding takes data from the internet and points it to one Local Net Ip adddress (Coputer)
Port Triggering uses one por to recieve data to then open more ports and can be used by many computers on your LAN.
See September 7th
http://www.ralphjohnsuk.dsl.pipex.com/blog.html here for the ports required for the MAc Firewall if On and Port Forwarding
Port Triggering can be done like this for your device
http://portforward.com/english/routers/port_triggering/Netopia/Cayman3346/iChat. htm
Ignore the Brown and yellow bits at the top.
Generally it is set up like this
Port 5678 triggers port 5060
Prot 5060 triggers ports 16384-16403
The Netopia is not quite the same as other devices so follow the instructions above.
Ralph