I have recently migrated from a DSL line to an alternative form of internet connection (basically, it's ethernet).
I was hopefull that I wouldn't have to ditch my WAG54GP2 V2 router for something like a PAP2, but I coudn't find anywhere the linksys config to specify an alternative default route (that doesn't go via it's DSL interface).
Last night I figured out the answer - the WRT54GP2 doesn't need to have a full default route, it only needs to be able to route to the VFX servers!
The trick is to deselect the "Enable Now" option under the DSL configuration, then set up a static route to the 22.214.171.124/8 network under "Advanced Routing" via the main router. This allows the WRT54GP2 to route to the VFX servers via it's internal ethernet ports (and via my new ethernet router) rather than out via the DSL. Bingo - my VoIP line is running again :)
I did enter port-forwards in my other router for UDP ports 8060 and 35300-35600 through to the internal IP of my WRT54GP2. This wasn't necessary to get outgoing service operational, but it helps for incoming calls when the NAT tables have timed out (or after a reboot of the main router etc). I'm sure those port ranges could be narrowed significantly - any help with regard to this is appreciated :)
Hope this helps someone!