I have an Australian SIM card, even living in Germany. The main reason is to save money on a Data when I am in Australia and to communicate with my friends when I am downunder. Then it is my contact number for QF. The code is not a problem as receiving SMS overseas is free of charge. I use it in an old spare phone and switch it on from time to time. There may be cheaper options, but I have the same number since 10 years which makes it easier for my friends to contact me. One call from Qantas Chauffeur Service on my German number in Australia is equivalent to quite a few MB on my Telstra prepayed.