If you’re using dual SIM (multiple services on one device), be aware of your primary and secondary number settings. Either mobile number could potentially incur International Roaming charges.
When travelling overseas with a device that has more than one service installed, it’s a good idea to familiarise yourself with how dual SIM works on your particular device to stay in control of your usage and roaming costs. You may already be using dual SIM in Australia, or you may create a dual SIM set up while overseas if you add a local SIM on the same device as your existing Telstra service.
You can disable International Roaming for each Telstra service independently however this will not prevent charges from being incurred if Voicemail/MessageBank is used for any of your Telstra numbers.
To ensure no costs are incurred by temporarily switching off or removing a service on eSIM from your device, refer to the instructions for dual SIM number management from your device manufacturer, including Apple, Samsung and Google. This should be done before you leave Australia.