What does your inbound link distribution look like in terms of paid/organic links? Also, be careful with using the same anchor text on links back to your site. Google is getting better at detecting what can only be described as "over optimization" and the number one indicator is "perfect" anchor text usage.
If you are buying/trading/reciprocal linking, try varying up your anchor text, using things like "conference", "call", "Free" along with "conference call."
I would also play with some <H2> and <h3> tags using your desired kw phrases on your home page.
There are a few other things you can do if you have the time....ping me if you want a full list.
