The router has done wonders for my LAN but nothing can help my crappy DSL service. It may be possible to bypass your router functions Arctos. I assume you are still with Optus so if I read correctly then they allow you to roll you own. Looks like if you do then they won't support your chosen modem and router but if they are anything like AT&T then the support is next to useless anyway.
Aye, AT&T wanted to push the VOIP service on me a few weeks back. I told them if I wanted VOIP I would ditch all of their services and go cable for internet and use Skype or one of the cheap VOIP services for phone. The salesman shut up real quick.