We're with iiNet Naked DSL. They moved our original land-line number to the VOIP line.
I've not tried faxing over VOIP but I did note that there were some 'challenges'. I've got a HP Laserjet m2727nf combo scanner/printer/fax.
A couple of things you'll want to do if things don't work...
We got rid of our land line ages ago. We moved the original land-line number to the VOIP line so callers didn't notice anything.
We have a crappy ADSL service though outside of the house and it's just the way it is here. The junction box had flooded a few years back due to some road works...
