There are a number of service providers in Australia and they offer varying plans, rates and coverage. Our 3 main providers are Telstra, Optus and Vodafone. Vodafone offer excellent international calling rates however their coverage is not as wide. You can purchase a SIM card from phone shops in shopping malls. Some supermarkets, corner stores, post offices and 7-Eleven service stations also sell them. You will need identification and know the Australian address you will be staying at to activate the SIM.