The Iridium network has very good coverage throughout Australia and most of the globe. The 9575 requires the aerial to be pulled up and pointing towards to the sky to be able to maintain best coverage. The phone is unlikely to receive network coverage when in a vehicle / building or other type of natural or man-made structure. There may also be limited coverage when in a ravine or gorge, however given the Iridium network is constantly rotating the globe, there is a possibility of some coverage allowing the ability to make a brief call or send a text / SOS if an emergency.