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What is an eSIM and how does it work?

Close up of Woman using a phone with eSIM technology in a cafe.

Pretty soon SIM cards will be little more than a relic, but we've got all the details you need to know on their replacement – the eSIM

For decades there has only been one way to connect a phone to a mobile network: the SIM card – a little bit of plastic and metal that held the key to the network. Originally the size of a credit card, they’ve shrunk drastically over the years, but now, with the rise of the eSIM – an all-electronic replacement – they face their inevitable extinction.

If you’re curious about what an eSIM is and how it works, read on. We also spoke to Kester Mann, director of consumer and connectivity at the technology analyst company CCS Insight, about what impact eSIM will have on the industry.

How does an eSIM work?

A SIM (or ‘Subscriber Identity Module’) card contains a chip that verifies your identity so that you can access a mobile network. An eSIM card performs this exact same core function but, instead of being set in a piece of plastic that you manually insert into your phone, an eSIM (‘embedded SIM’) is software on a chip built directly into your phone’s hardware, which can then be reprogrammed with new SIM information afterwards.

The advantages of an eSIM

There are several advantages to eSIM cards, and it’s actually a challenge to think of many downsides.

Even before we get to the technical benefits, they’re great from an e-waste perspective – they cut down on the production of SIM cards and all the attendant packaging and junk that typically comes with them.

A main part of the attraction of eSIM compatibility is that you can swap between network providers easily and without any delays, with no need to go to a store or wait for a physical card to be posted out. And, in many cases – particularly with modern iPhones or Android phones – you can also have more than one network account active at once since swapping between these is a lot simpler when there’s no SIM card to extract.

A set of SIM cards on a white background. Interestingly, when we talked to Kester Mann, of CCS Insight, he pointed out another lesser-known advantage: “An eSIM also helps prevent fraud. As the SIM card is embedded in the hardware, it is no longer possible to separate a subscriber’s identity from their device.”

If there are downsides, the main one will be that when you want to change phones, rather than networks, there may be a few more hoops you’ll need to jump through.

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What phones use eSIM?

eSIM compatibility has become all but ubiquitous over the last few years, and practically all manufacturers’ flagship devices now support it.

Google has offered eSIM support in their Pixel phones since 2017, while iPhones have supported it since 2018, and Samsung added it to its Galaxy range in 2020. In fact, as of the iPhone 14, Apple only uses eSIM in the US, however this change hasn’t gone worldwide yet.

However, it’s not guaranteed that the feature will be available across a manufacturer’s entire range – if you’re interested in a particular model of phone and you’re curious about whether it works with eSIM, the smartest thing to do is go to the manufacturer’s website and look up its specs.

Is eSIM good for roaming?

Roaming is one of the very best aspects of having an eSIM-ready phone. In years gone by, if you were smart, your first act upon arriving in some far-flung country was to find a cheap SIM-only deal to access the local mobile data network. Now, instead of scrambling around street stalls or looking in shops that might sell you the wrong thing, you can do your research in advance and get a plan for the local area lined up and ready to add to your phone the moment you get off the plane.

This can not only save you plenty of cash but be far less fiddly than swapping physical SIM cards over – especially considering that you’d have to carry a SIM card tool with you and find somewhere safe and secure to store the tiny SIM you remove.

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How to set up an eSIM

Setting up an eSIM card is relatively straightforward whether you’re on iPhone or Android, the steps differ slightly for each, though.

On an iPhone, the process requires you to go to Settings, and then Mobile Data (or Mobile Service in the UK). From there, you should be able to see an Add eSIM button to tap on, which will start the process. Then it’s just a matter of matching your chosen mobile network’s instructions to the iPhone’s, which should involve scanning a QR code.

On Android phones, the process can differ between manufacturers. For example, if you have a Samsung phone, you need to head to Settings, then tap on Connections and then SIM Card Manager. Next, choose Add Mobile Plan and follow the steps according to your mobile network’s directions – again, a QR code is likely the best way.

If you’re on another type of phone, the process is likely to be similar but you may find the stages are labelled differently. In which case, the easiest way to find out how to add an eSIM to your phone is to head to your manufacturer’s website and check out their online resources.

What iPhone models support eSIM?

Apple has been throwing its weight behind the eSIM revolution for a few years now and, as we already mentioned, has supported the feature since 2018.

Any iPhone later than an iPhone Xs, iPhone Xs Max or iPhone XR will support eSIM, and if you buy a new iPhone 14 or iPhone 15 in the US, you’ll only have eSIM as an option.

Each iPhone can have plenty of eSIM cards attached to it too – Apple says you can use “eight or more” – though, for making or receiving calls, you’ll only actually be able to use two at once.

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Should I use eSIM or normal SIM?

At this point, the question of which is better between a digital eSIM and a physical SIM card comes down to personal preference.

As Kester Mann puts it: “The most tech-savvy people will probably want to swap to eSIM but other people will need to be supported along the journey. eSIM necessitates new learning for customers who have become familiar with the traditional – if clunky – process to insert a physical SIM card into a tray.”

If you actually like the task of swapping a physical card between multiple devices and that’s something you need to do often, then there’s a clear case for sticking with a traditional SIM card. For most people, that’s not a regular concern and being able to do away with physical cards will have no downside, while the upside is you’ll be familiar with setting up an eSIM card ahead of any business trips or holidays – potentially handy to avoid roaming charges.

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