When travelling overseas, using a data-only international eSIM is a highly cost-effective way to stay connected. By utilizing your smartphone's Dual SIM functionality, you can run an international data eSIM alongside your standard Australian mobile service.
This guide ensures you can use your new international eSIM for affordable data while keeping your Australian SIM active to receive important text messages (such as bank OTPs and security alerts) for free without triggering accidental roaming charges.
Device Compatibility: Ensure your smartphone is carrier-unlocked and supports eSIM technology.
Data-Only Context: Most travel eSIMs are data-only. They do not include a local phone number for standard voice calls or outbound SMS.
Complete these steps just before your flight or immediately upon landing at your destination.
Open Settings > Mobile (or Cellular).
Ensure both your Australian Primary SIM and your International eSIM lines are turned ON.
Tap on your Australian Primary SIM:
Toggle Data Roaming to OFF. (Crucial step: This completely blocks your Australian carrier from charging you for internet usage while abroad).
Go back to the main Mobile menu and tap Mobile Data:
Select your International eSIM as the default line for your data.
Tap on your International eSIM profile:
Toggle Data Roaming to ON. (Most travel eSIMs require roaming to be on for their profile to access local partner networks).
Turn OFF "Allow Cellular Data Switching" at the bottom of the Mobile Data screen. This prevents your iPhone from accidentally failing over to your Australian carrier if the local network coverage dips.
Open Settings > Network & Internet > SIMs (or Mobile Network).
Ensure both your Australian SIM and your International eSIM are toggled ON.
Tap on your Australian SIM:
Toggle Data Roaming to OFF.
Go back to the SIMs menu and locate your default network preferences:
Set Preferred SIM for Mobile Data to your International eSIM.
Leave Calls and SMS preference set to your standard Australian SIM.
Tap on the International eSIM profile:
Toggle Data Roaming to ON.
While receiving incoming SMS is entirely free on Australian mobile services while roaming overseas, specific user actions will trigger automatic, expensive daily roaming fees from your domestic carrier.
Do Not Reply to SMS: You can safely read incoming bank codes or texts. However, do not reply to a standard SMS text message while abroad.
Do Not Answer Calls: Reject or ignore standard incoming mobile calls. Answering a call—even for a few seconds—will instantly trigger your Australian carrier's daily international roaming pass.
Use Data Apps for Daily Communication: For day-to-day messaging and calls with friends and family, strictly use internet-based applications like WhatsApp, Apple iMessage, FaceTime, or Viber. These apps will route seamlessly through your international travel eSIM data connection without affecting your Australian line.