So let me get this straight.
You want me to go buy an IP Faxmachine so you can fax to me?
It seems to me someone is not explaining how things work to you. FAX is still over POTS (read http://en.wikipedia.org/wiki/Plain_old_telephone_service ) Since all you need is to toss your fax onto your phone line there is no new hardware to buy.
Again, that jack you plug your old phone into is where you plug your fax into.
I know this works with my Comcast phone service. It may be VOIP but they install their own MTA so it's transparent to me.