GizmoChina Explains: How Does An eSIM Work?

by Habeeb Onawole 0

This year, three devices were launched with an eSim -the Apple Watch 3, the Pixel 2 and the Pixel 2 XL. Add them to last year’s Samsung Galaxy Gear S2 3G and the iPad 9.7, the first two devices to come with what is called an eSim and that makes it five. For this new technology, this is just the beginning.

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An eSIM/eUICC (embedded SIM or embedded UICC) is a replacement for the current physical SIM cards that we use in our smartphones and a bunch of other devices. While users can remove the physical SIM cards in their phones, an eSIM cannot be removed. Most people do not know how an eSIM works, this post is aimed at explaining how it works and the benefits it brings to consumers.

Evolution of SIM Cards

Ever since mobile phones became mainstream, users had to buy a SIM card from their preferred network operator to be able to use their services. The SIM card had a number attached to it and a security key that allowed the network to identify and authenticate subscribers of its services. It can also store contacts and text messages. Over the years, the physical SIM card has reduced in size. Starting first as what is today called the Mini SIM, then getting a reduction to what is called the Micro SIM and finally the Nano SIM. All three SIM types are still in use but the last two are the common ones used by smartphones.

Samsung’s Gear S2 Comes With eSIM support

So why has the size of the SIM reduced over time? To create space. Smartphones have gotten thinner over the years and space has become so precious. The Mini SIM takes a lot of space along with the tray and the reduction in size makes it possible for manufacturers to fit more components on the device or better still, create a thinner device.

How eSIMs Work

With the use of an eSIM which is a fraction of the size of a nano SIM and the complete elimination of the SIM tray, there is more space for other components as well as an overall thinner device.

Apart from space, eSIMs will also allow users switch between networks with ease. This is different from roaming (you don’t pay roaming charges) and is done over the air. eSIMs will be able to store different network profiles and consumers will be able to switch easily between networks. How this is supposed to work is that you should have multiple profiles on your eSIM and switch between any of them easily. So you can have a data plan on one SIM profile and a voice plan on another SIM profile, and because it is the same number, calls and SMS are not missed.

smartphone search

For easy switching, there has to be a unifying standard that makes it easy for SIM profiles to be loaded on the eSIM. The GSMA has a standard called Profile Interoperability which simplifies the process and makes the relationship between operators and OEMs more flexible. There are hundreds of operators all over the world with different SIM profiles, so it is only logical that there is a standard that everyone can adopt. The two videos below explain how this is supposed to work.




While the Pixel 2 and Pixel 2 XL’s eSIM works on only Google’s Project Fi network for now, the Apple Watch 3 can be used on Verizon, T-Mobile, or Sprint. Users should be able to keep their mobile numbers when they switch but they may be charged a fee when moving to a new operator for the first time. This fee will be similar to what you pay when you purchase a SIM but may include free data and voice calls too in the package.

sim card on a pc

The Future of eSIMS

It may take a while for eSIMs to be adopted widely for smartphones, but it will be easier to adopt into devices like wearables, cars, and computers which require mobile connectivity. Microsoft and Qualcomm’s upcoming ARM-powered computers are expected to have eSIMs for on-the-go connectivity. Microsoft also announced that its new Surface Pro will come with LTE via an eSIM but that version won’t arrive till Spring next year.

For Windows PCs with eSIMs, users will be able to purchase data plans from the Windows Store. T-Mobile, AT&T and some other foreign operators have already signed on to work with Microsoft on this.

There are still some concerns associated with the use of eSIMs. Let’s say your phone is low on battery and you have a traditional SIM card, you could simply remove the SIM and put it into the other phone. For devices with eSIMs, you can’t do that.

READ MORE: Broadcom’s Highly Accurate GPS Chip Arriving in Smartphones Next Year

Also, the switch to eSIMs doesn’t mean the death of carrier-locked devices. The reason for carrier-locked devices is because the owners are on a contract plan and are obliged to pay monthly installments for the phone. It makes it easy for folks to get a new phone and not have to shell out the cost at once. However, they will be able to switch to any network of their choice when their contract expires.

What are your thoughts about eSIMs? Are there any problems you think they might pose that we have failed to mention? Please drop a comment in the box.

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