As I prepare and plan for my photographic trips next year I always invest a lot of time into researching locations, getting maps and since this is the first time I will be heading out into remote areas I need to think of safety and supplies.
I found the following info from the Australian Government website (www.telinfo.gov.au) regarding an emergency contact number that uses the GSM network when you dial it from your mobile phone, so you might have no signal to make a normal phone call but there might be GSM coverage that your mobile will pick up when you dial 112. This number can even be dialed when the phone phone key pad is locked, just like 000.
So if your stranded and running out of contact options then remember 112.
As always a good travel plan and letting people know where your are going and when you should be back is also a critical part of your trip planning.