Lots of problems with the Australian Networks
It should work if you have an approved phone and 4G calling activated, but it seems some are being caught out
Try connecting to Vodafone, but read this carefully and follow any links
https://community.o2.co.uk/t5/Discussions-Feedback/Roaming-in-Australia/td-p/1765855
This is not O2 and we are all customers here similar to yourself and cannot answer account type queries.
