The Australian Outpost Radio Service is an HF network monitored by RFDS stations around the country. It's primary purpose is to provide emergency assistance to remote areas whose main means of communication with the rest of the country is either by satellite or HF radio.
The Outpost network also provides a Radphone service run by Telstra, similar to the Seaphone service, which provides phone patches to users in the field.
Mainly 4WDers (ANFWDC), cattle stations, mines and the like utilize the network for vehicle-to-vehicle and vehicle-to-base communications. You may have seen 4WDs with their massive tapped antenna on the front, this is for an OUTPOST radio.
All radio's are licensed to a maximum 100W pep and operate on USB
People have also found that the OUTPOST license is much more convenient than applying for an amateur license and therefore many "HAM" operators appear on the frequencies. For more info www.aca.gov.au - Search for OUTPOST NON-ASSIGNED LICENSE

Various stations monitor set frequencies, these are shown below:

FREQUENCIES (KHz)

Australian National Four Wheel Drive Council (ANFWDC)
5455 (AUS WIDE)

Northern Territory
VJY Darwin
2360
4010
6840
7975

VJD Alice Springs
2020
5410
6950

Western Australia
VJB Derby
2792
5300
6945

VKL Port Headland
2280
4030
6960

VJT Carnarvon
2280
4045
6890

VKJ Meekatharra
2280
4010
6880
11466

VJQ Kalgoorlie
2656
5360
6825
Duplex 8144 / 7550

South Australia
VNZ Port Augusta
2020
4010
6890
8165

Queensland
VJN Cairns
2020
2260
5145
7465

VJI Mt Isa
2020
2260
5110
6965

VJJ Charleville
2020
2260
4980
6845

New South Wales
VJC Broken Hill
2020
4055
6920

VZX Penta Comstat (Gosford)
Penta Comstat has wide ranging frequencies that cover most of Aus. All channels are scanned 24hrs a day, ch836 for voice calls 7am-10pm and 429 from 6pm-10pm.
Land&Marine Radiophone channels:
429   -  4354 SIMP
608   -  6552 RX / 6221 TX DUP
836   -  8713? 8294? SIMP
1234 - 13476 RX / 12329 TX DUP
1642 - 17356 RX / 16483 TX DUP
2243 - 22822 RX / 22126 TX DUP