Dual SIM Travel iPhone Tips: Keep Your AU Number Active

To keep your Australian number active for SMS while using travel data, you must use your iPhone’s Dual SIM capability to assign your home SIM as the 'Primary' line for calls and texts while using a travel eSIM for all 'Cellular Data.' This configuration allows you to receive bank 2FA codes and important texts on your AU number while avoiding the $10-per-day roaming charges from home carriers by routing all internet traffic through a local network. AussieRoam provides the data-only eSIMs needed to make this setup seamless for travelers heading to Bali, Japan, or Europe.

The Roaming Trap: Why Your Home Carrier Wants Your Money

If you are a Telstra, Optus, or Vodafone customer, you have likely seen the advertisements for 'International Day Passes.' They sound convenient—pay $10 or $15 a day and use your phone just like you do at home. But for a two-week holiday in Japan (dest:jp) or a month-long stint through Europe (dest:eu-42), those daily charges add up to a massive bill. Even worse, if you accidentally go over their small daily data caps, the extra fees can be eye-watering.

The real kicker is that these carriers aren't providing their own network abroad; they are just leasing space from local providers and charging you a massive premium for the privilege. By using a travel eSIM, you bypass the middleman. You connect directly to local towers in Thailand (dest:th) or Spain (dest:es) without the 'roaming' tax. AussieRoam offers data-only plans that give you the same local connectivity without the daily fee, but the trick is setting up your iPhone correctly so you don't lose access to your Australian identity.

How Dual SIM Works on Your iPhone

Most iPhones released since 2018 (the iPhone XS, XR, and newer) feature Dual SIM technology. This means your phone can have two different cellular plans active at the same time. Typically, Australians have a physical SIM card from their home provider and an empty eSIM slot. This is the 'holy grail' for travelers. You keep your Australian SIM in the tray to receive those crucial SMS messages from your bank or MyGov, and you check if your phone is compatible to download a travel eSIM for everything else.

When you land in a place like Bali, your phone will see two networks. You simply tell the iPhone: "Use my Australian SIM for phone calls and SMS, but use this AussieRoam eSIM for all my Instagramming, Google Maps, and WhatsApp calls."

Keeping Your AU Number for 2FA

One of the biggest headaches of traveling with a local physical SIM card used to be taking your Australian SIM out. The moment that tiny piece of plastic leaves your phone, you lose your Australian number. If you try to log into your banking app and it sends a verification code to your mobile, you’re stuck. With a Dual SIM setup, your Australian number stays 'On.' As long as you don't answer incoming calls or send outgoing texts, most Australian carriers won't trigger the daily roaming charge just for receiving a standard SMS.

Step-by-Step: Setting Up Your Travel eSIM

To get the most out of your trip, we recommend installing your eSIM while you are still at the airport in Sydney, Melbourne, or Auckland. You can follow our how it works guide for a deep dive, but here is the quick version for iPhone users:

1. Purchase and Scan: Once you buy your AussieRoam eSIM, you’ll get a QR code. Go to Settings > Cellular > Add eSIM and scan it.
2. Label Your Plans: This is crucial for staying organized. Label your home SIM as 'Primary' and your travel eSIM as 'Travel' or 'AussieRoam.'
3. Set Default Voice Line: Choose 'Primary.' This ensures that if you need to make a call, it defaults to your home number (though keep in mind, this will incur charges).
4. Set Cellular Data: Choose 'Travel.' This tells your iPhone to use the eSIM for all internet traffic.
5. Turn Off 'Allow Cellular Data Switching': This is the most important step. If this is 'On,' your iPhone might jump back to your Australian SIM if the local network flickers, leading to a surprise bill from Optus or Telstra.

Android Setup (Samsung/Pixel)

For those on the other side of the fence, the process is similar. Go to Settings > Network & Internet > SIMs. Tap 'Add' or '+' and download your eSIM. Once active, ensure your AussieRoam eSIM is selected for 'Mobile Data' while your home SIM remains active for 'Calls' and 'SMS.' Android handles Dual SIM quite well, and you can usually see two signal bars at the top of your screen.

Local Carriers and Coverage Realities

When you travel, coverage isn't always equal. Here is what to expect in our most popular destinations:

• Bali: In built-up areas like Seminyak or Kuta, coverage is fantastic. If you are heading out for a Sidemen Bali Travel Guide experience, you’ll find that Telkomsel (the carrier AussieRoam often partners with) has the best rural reach.
• Japan: You’ll likely be on the SoftBank or Docomo networks. These are world-class. Even on the Shinkansen (bullet train) between Tokyo and Osaka, your data should remain stable.
• United Kingdom: Coverage in London is great, but if you are taking day trips from London by train, you might hit 'dead zones' in the deep countryside of the Cotswolds. AussieRoam eSIMs will hop between the best available towers in the UK (dest:gb).
• Europe: Most of our Europe plans cover 42 countries. You can cross the border from France (dest:fr) to Italy (dest:it) without even restarting your phone; it just works.

Managing Your Data Usage

Since our plans are 'data only,' you won't get a local phone number. This isn't an issue for 99% of travelers. Everyone in Bali uses WhatsApp, and in Japan, LINE is king. You can make crystal-clear voice and video calls through these apps using your AussieRoam data.

To make your data last longer, turn off 'Background App Refresh' for apps you don't need. TikTok and Instagram are data hogs—if you're scrolling videos on the bus in Thailand (dest:th), you'll burn through a gigabyte faster than you think. Save the heavy scrolling for the hotel Wi-Fi.

Comparison: Roaming vs. AussieRoam eSIM

Feature	Telstra/Optus Roaming	AussieRoam Travel eSIM
Cost	$10 - $15 per day	One-off prepaid cost (No hidden fees)
Data Limits	Often capped at 1GB/day	Large bundles (up to 20GB or more)
Network	Roaming Partner (can be throttled)	Native Local Networks
AU Number	Active (but expensive to use)	Active for SMS (using Dual SIM)
Setup	Automatic (Dangerous)	Manual Control (Safe)

The bottom line

You don't have to choose between keeping your Australian number and having affordable data. By using the Dual SIM settings on your iPhone or Android, you can enjoy the best of both worlds. Install your AussieRoam eSIM before you fly, keep your home SIM on for those vital SMS alerts, and spend your money on experiences rather than roaming bills. It’s the smartest way to stay connected while exploring the globe.