Australians in general love all new technology and as such our mobile phone network is very well established. However due to the size of Australia, and the sparesness of population in some areas, really good coverage is generally limited to the cities, with dropouts and areas of no coverage common in rural and remote areas.
It is recommended that you activate global roaming on your existing mobile prior to embarking on your travels as this will ensure that you have access to communications when you arrive. This option can be expensive, and is not recommended for extended periods.
Getting a phone on a 'plan' provided by the local telecommunications providers can be difficult if you are a temporary resident, so the most common option is to purchase a 'pay as you go' SIM card, which can be topped up via numerous options, quite often including the local corner shop.
'Pay as you go' SIM cards can be packaged with reasonable phones, or can be inserted into your own phone. The majority of overseas phones are compatible with the Australian networks, but it is advisable to check.
Your Latitudes Consultant can provide you with further advice regarding your needs and options.