What is an eSIM? Here’s everything you need to know

The iPhone Xs comes with an eSIM — here’s what that means

Guide to the eSIM

The humble SIM card has survived for quite a while, but it now finally looks like it’s on its way out. Why? Well, the eSIM, a much smarter technology, is here to save the day.

Before we dive into what an eSIM is, it might be helpful to understand what a SIM is. A SIM, which stands for “subscriber identity module,” basically contains the information that authenticates your identity to a carrier. In other words, the SIM card is what tells a carrier that you’re you — and without it, carriers wouldn’t know that you’re subscribed to their network, and thus wouldn’t let you use their cell towers.

But learning about a standard SIM card isn’t why you’re here. Here’s everything you need to know about the new eSIM.

What is an eSIM?

An eSIM is exactly what it sounds like — an electronic, or embedded, SIM. Instead of a physical card, SIM technology is built right into your phone. It’s a small chip that’s used to authenticate your identity with your carrier.

Of course, you probably have some questions about that. With a traditional SIM card, you had to switch the SIM if you traveled and used a new carrier on your travels, or if you wanted to switch carriers. So does a built-in SIM mean that you have to switch phones? Thankfully, no. In fact, one of the advantages of eSIM technology is that it makes it much easier to switch carriers. Instead of having to order a new SIM and wait around for it to arrive, you can switch to a new carrier straight from your phone. If you’re a dual-SIM user, eSIM technology supports multiple accounts — and switching between them is super easy.

Those are the promises made by the GSM Alliance (GSMA), but what that will look like isn’t known just yet. It’s likely your phone will have a few new settings menus devoted to your SIM card, and will allow you to switch carriers and manage accounts straight from your phone. The Google Pixel 2 was among the first phones to support eSIM technology, and an app for managing your eSIM is available from the Google Play Store. Then, the iPhone Xs came out, and it offers both a physical SIM card and an eSIM as a secondary, though the eSIM will only be enabled later down the line through an iOS software update. Unfortunately, the Chinese version of the iPhone does away with the eSIM altogether — instead offering a dual-SIM slot. That could suggest that Chinese carriers are less interested in adopting the new tech, which is bad news for those that were looking forward to using an eSIM to travel to China.

The eSIM will be helpful for another reason — it will help make devices smaller. Now, that may not matter all that much for phones (although a little extra room for battery capacity is always nice), but it could be extremely helpful for wearables. The Apple Watch Series 3 and Series 4 actually already have eSIMs, and that is partly how Apple managed to keep the device pretty much the same size as previous generations of the Apple Watch.

When can I start using an eSIM?

It may be a while before the full potential of the eSIM is realized. Some handset manufacturers, like Apple, have started building eSIM tech into their products, but carriers have to support it too. That’s not just carriers in the U.S. either — considering eSIMs are arguably most useful when you’re traveling, it would be nice to see carriers around the globe adopt the technology. And that could take a while.

It is likely that eSIMs will also find a home in a new generation of LTE-connected computers. Those computers are just now starting to come out — but expect to see a lot more of them in the next few years.

Still, slowly but surely eSIMs will take over. If your carrier supports it, and your phone supports it, then that may be all you need to start using the new technology. For now, it’s likely that phones with eSIMs will still have traditional SIM card slots, but eventually those trays could go away altogether.

Updated on September 13: Added information regarding the iPhone Xs having an eSIM.

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