The title and question were somewhat difference
here is the Australian ham radio band plan. hflink.com/bandplans/australia_bandplan.pdf
The bands are very similar to US ham bands. Most ham bands are similar. Some chop the bands at one end or the other. Band plan and license class usage will vary but freq are pretty static.
For Australian there is a HF outback radio system that is used. You have been directed to those in other replys. Those are more a network of users. Long range communications service. There is one managed by the 4x4 clubs, one for the flying doctors and a couple of commercial ventures. The only thing close in the US is the single Alaska emergency frequency 5167.5 kHz but that is only usable in AK and only for emergencies.