What is an eSIM and how does it work?

A SIM identifies you to a mobile network, so your phone can make calls and use data. For years that meant a small plastic card in a tray on the side of the phone. An eSIM does the same job, but it is built into the phone and you load a plan onto it over the internet.

What an eSIM is

Apple, Google and Samsung each describe an eSIM as a digital SIM that is built into a compatible phone, so you can add a mobile plan without a physical SIM card.

The standard behind it comes from the GSMA, the mobile industry body. It says a SIM can now be securely downloaded into a secure element that is permanently embedded in a device, with a level of security equivalent to a removable SIM card.

How an eSIM works

You choose a plan. It can be your own mobile provider's or a travel eSIM provider's.
The provider gives you a way to add it. On an iPhone that can be the provider's app, a QR code, or details you type in yourself in the mobile data settings. Android phones have a similar option in their SIM settings.
Your phone downloads the plan. You need an internet connection to do this, so install it over Wi-Fi at home before you travel. Apple says iPhones need Wi-Fi or a hotspot, though in some countries eSIM-only models can activate without it.
The plan appears as another line. You name it, turn it on and choose whether it carries your mobile data. The provider's own setup steps tell you any extra settings it needs.

Our set-up guide covers the steps for a travel eSIM.

One line or two

An eSIM does not have to replace your Australian SIM.

iPhone. Apple says an eSIM lets you manage up to eight or more eSIMs. iPhone 13 models and later support two eSIMs at once, and an iPhone that also has a SIM tray can use a physical SIM and an eSIM together.
Pixel. Google says a Pixel can store more than one eSIM profile, and a Pixel 7 or later can use two eSIM profiles at once if the carrier supports it.
Galaxy. Samsung says you activate an eSIM plan with your service provider, and lists the Galaxy models that support eSIM on its Australian site.

That is what lets you keep your Australian number for texts while a travel eSIM carries your data. See how to keep your Australian number.

How an eSIM differs from a SIM card

Nothing to swap. There is no card to carry, lose or wait for in the post. Apple also notes an eSIM can't be removed if your iPhone is lost or stolen.
Set up online. You add or change plans from the phone, rather than by changing a card.
It needs a compatible phone. Not every phone supports eSIM. See which phones support eSIM.
It needs a provider that sells eSIMs. Apple lists a provider that supports eSIM as a requirement alongside the phone.
The phone must be unlocked to use another company's eSIM. Apple says an iPhone locked to a service provider can't be used with another provider's plan while you travel.

Why travellers use one

Roaming on your Australian plan can be very expensive. The Australian Communications and Media Authority says the cost of international roaming for calls, texts and data can be very high, and suggests asking your provider about roaming passes or, if you can change the SIM in your phone, buying a local prepaid SIM. A travel eSIM is a way to get a data plan for your destination without handling a card. Apple notes you can buy a prepaid plan online before you travel.

An eSIM is not always the right choice. Travel SIM card or eSIM compares the options, and the roaming calculator compares your carrier's day pass with the cheapest eSIM for your trip.

Sources

Next: check your phone supports eSIM, then see the best travel eSIM for each destination, such as Japan or Thailand.