A UC box will be perfect for you man. They can run 8 or 16 handsets depending on the model.
You could use a Cisco UC5X0 as they have 4 fxo ports on them to emulate a analog line over SIP, that is what we do for our fax/modems. Telstra don't officially support it though.
We use Telstra for the data but we manage the services/equipment.