I recently travelled to Hong Kong for ten days. This has traditionally meant a reliance on hotel WiFi for communications; on a local SIM for voice calls, with usurious call rates to and from home. Using Australian data overseas is a fast path to financial ruin.
The world has changed.
I arranged a Telstra “International Travel Pass” prior to leaving. It can take a few days to activate, so plan ahead.
(Your phone will work overseas without it, but that’s a little more expensive; and data is a hundred times more expensive. Really.)
I purchased the 14-day Zone 2 pass for $140. People rang me; I rang them… it was like being in Australia still.