Since they first hit the market, smartphones have required a SIM (Subscriber Identity Module) card to connect to a carrier and identify users on the network. But if you’ve bought a device in the last few years (like the iPhone 16), you may have noticed that it uses an eSIM, or built-in SIM card, instead of the traditional physical card.
With an eSIM, your data is stored on a chip in the phone, rather than on a card that you can swap in and out. This chip can be reprogrammed as needed, so tasks like changing songs are faster and more convenient, and not much changes in terms of the actual user experience.
While SIM cards still exist, eSIMs are very much the future. Here’s what you need to know about them and how they work.
How an eSIM works
The shift from SIM card to eSIM may seem drastic, but the technology is actually very similar: you simply use a reprogrammable integrated circuit in your phone instead of an integrated circuit on a physical card that you can see and hold (and switch between handsets) . All the information the eSIM needs can be taken from the internet, instead of being written on a card.
The most important information is your mobile number and the associated identity and data subscription. Your eSIM allows you to make and receive calls, send and receive text messages, and go online when you’re not connected to a Wi-Fi network. Once the initial setup is complete, you won’t notice any difference between using an eSIM or using a traditional SIM card.
Using an eSIM means you can set or change a number without having to wait for a new card to arrive in the post (although it’s not as fast as carrying two physical SIM cards and simply switching one in front of the other change when necessary to). For example, it can help when you are traveling, because you can order and set up a new country-specific eSIM on the Internet in just a few minutes, without ordering a new card.
Many phones support multiple eSIMs, allowing you to manage multiple numbers at once. And here’s another benefit: you don’t have to worry about losing your SIM card eject tool, or spend time looking for a spare paperclip if you lose it. Changing SIM cards is as easy as changing accounts in your email app.
Users in different parts of the world have different habits and different requirements, so the physical SIM card will be around for a while. In the long term, however, eSIM will become the norm not only on smartphones, but also on other devices such as tablets, laptops and drones. Without a SIM card slot, gadgets can be smaller or have more room for extra storage or larger batteries.
How to set up an eSIM
If your phone supports eSIMs, you’ll see options to configure this when you set up the phone for the first time: to add a new eSIM or to transfer one from another device. If you bought the phone from a carrier with a plan attached, all you have to do is tap through a few confirmation screens.
If you’re changing a number from another phone or setting up an eSIM on a handset you bought separately, it’s only a little more complicated. The carrier you purchased the eSIM from should give you full instructions on how to get it working. This usually involves an activation code that proves that you are who you say you are.
On an iPhone, go to Settings and then choose Mobile And Add mobile subscriptionto configure an eSIM. If you already have a plan, you will see it Add eSIMwhich starts the same process for an additional eSIM (you can have up to eight on the same iPhone). If you are using an older model with a physical SIM card, there is one too Convert to eSIM option.
Android, meanwhile, offers much more eSIM support and many more software settings. The Google Pixel 9, for example, supports both a physical SIM card and one or two eSIMs. You can configure eSIMs by going to Settings and then choosing Network and internet, SIM cards, Add SIM cardAnd Set up an eSIM. Again, just follow the instructions for entering the activation code or scanning the QR code from your eSIM provider.
When it comes to moving your number from an old phone to a new phone, the eSIM process is not as fast as the SIM card method. You must contact your carrier for exact instructions. This usually concerns instructions a few clicks on your provider’s website—to indicate that you are switching phones. Then you just need to set up the eSIM on the new handset as described above.