Yes. The app is a great way to have easy access to your accounts no matter where you are.
The app must be registered using an Australian registered mobile number. The device must have international roaming to be able to use the app overseas.
Note: International roaming can result in excessive data usage charges. Contact your service provider to clarify these charges and how to minimise them.
Alternatively you can access the app over a Wi-Fi connection, however please consider the risk of using a Wi-Fi connection that you do not trust
(e.g. free Wi-Fi offered by Hotels and Cafes). Only use Wi-Fi hot spots that are reputable and password protected.