The country dialling code for Australia is +61.
The outgoing international code is 0011.
There are three mobile phone networks in Australia (Optus, Telstra and Vodafone). All three offer 4G services and most visitors from Europe and Asia will be able to use and Australian SIM in their existing handset. A number of smaller Mobile Virtual Network Operators also provide competitively priced pre-paid plans operating on one of the above networks. Most major providers have stores or stands at Australia's international airports; and more also offer phone and SIM packages for visitors without a compatible / unlocked handset. US visitors should check with their local provider with regards their phone's compatibility.
Mobile coverage is generally good around the major population centres, however some remote outback locations and islands do not have mobile coverage.