Australia has an IDD prefix or exit code of 0019 through Optus for fax calls.
Australia's IDD prefix is 0011 for voice calls and 0015 for fax calls. The IDD prefix is necessary to be dialled prior to the country code.
For those dialling from a country other than Australia, you will need to dial that country's specific IDD code. See IDD.com.au's International Dialling Codes page for the complete list of telephone country codes.
Find out how to call international numbers or make international calls from your cell phone or land phone. Prokerala shares the procedure to make international calls along with the International Dialing Codes and area codes you need to prefix to get an overseas call connected.