What is the difference between an eSIM and a physical SIM?

Many mobile phones nowadays have an eSIM option in addition to the regular SIM. In most cases, that means you end up with a dual-SIM phone where one of the SIMs can be an eSIM. As mobile phones and cellular devices such as smartwatches continue to evolve, eSIM is becoming a popular option to add the SIM capability. eSIM has also been a key topic for device manufactures for years. In this post, we will dive into the details of eSIM to find out what it means, how it works and how do you even know whether you have an eSIM capable phone or not?

eSIM (embedded SIM) is a programmable SIM built as a circuit board inside a 2G, 3G, 4G or 5G cellular device by phone manufacturers so you can programme it to a mobile network using a QR code; a physical SIM is a detachable plastic-based standard/micro/nano SIM that you manually insert into a phone.

What is an eSIM and how does it work?

eSIM stands for embedded SIM or embedded Subscriber Identity Module. It is a SIM that can be downloaded on a mobile phone, unlike traditional SIM cards where you have to insert a plastic SIM card into a mobile device physically. eSIM can be downloaded on an eSIM-compatible phone by scanning a QR code or entering the digital SIM information manually under phone settings. For an eSIM, a mobile phone has a microchip built into the phone that can be programmed to any mobile network operator as long as the phone is unlocked. Most eSIM capable smartphones (if not all) do not use eSIM as the primary SIM but instead as an additional SIM that can work alongside a conventional plastic SIM. Usually, you set up your phone as you normally do when you have a plastic SIM card, but there is an option to add an eSIM as a second SIM for your phone under phone settings.

What is the difference between an eSIM, micro SIM and a nano SIM?

A SIM or Subscriber Identity Module is basically an integrated circuit placed on a piece of plastic that you can physically insert into a mobile phone, tablet or other SIM-enabled device. Over the years, we have seen different SIM sizes, including standard, micro and nano SIMs. Nowadays, when we order a SIM card, we get a triple SIM card which basically means three SIM cards in one. With a triple SIM, a user gets one standard-sized plastic card where the chip (the metallic golden thing) sits in the middle, but the plastic around the chip is cut out in a way that allows a user to adjust the SIM size, as shown in the picture below. All modern smartphones with an eSIM capability usually have a nano-SIM slot where you can insert a plastic SIM as your primary SIM, but in addition, you can also download an eSIM by using the functionality built into the phone. A plastic SIM is a circuit board pre-programmed by a mobile operator to have certain account credentials. With an eSIM, the user can do this directly by programming the embedded microchip to a mobile network of their choice.

A triple SIM card that can be adjusted to become a standard SIM, micro SIM or nano-SIM.
A triple SIM card that can be adjusted to become a standard SIM, micro SIM or nano-SIM.

Does my phone have an eSIM?

When you buy a smartphone, this information is usually in the technical specs or features, but there are ways to find this out separately. Since most eSIM phones are also dual-SIM phones (phones with two SIM slots), you can run a quick IMEI check to determine how many SIM slots you’ve got. You can check your IMEI by typing *#06# on your phone’s dial-pad. If your phone displays only one IMEI, and if your phone already has a plastic SIM in it, that means that you don’t have an eSIM in your phone. However, if your phone shows two IMEI numbers, e.g. IMEI 1 and IMEI 2, that means you have multiple SIM slots, and one of them can be an eSIM. The eSIM information is typically under ‘Settings’ and then ‘Mobile Network’ or ‘Mobile Data’ depending on your phone. If your phone has eSIM capability, it will show you the option to download a SIM or scan a QR code. Here is a screenshot from Google Pixel 5, which is an eSIM capable phone. In Google Pixel 5, you need to go to Settings, then Network and Internet, then the + sign next to Mobile network, which will take you to the screen where you have the option to download an eSIM. When you tap “Download a SIM instead“, you will be taken to a guided screen where you get the option to scan the QR code available from your operator.

Google Pixel 5 eSIM option
Google Pixel 5 eSIM option

The other option to find out whether your phone has an eSIM capability or not is to use the GSMArena website, where you can type your phone’s model number to see all the detailed specs. The SIM information is displayed under the ‘Body’ section in the specs alongside the phone’s dimensions and weight.

Is eSIM better than physical SIM?

eSIM is the future because as more and more cellular devices get introduced, especially when the 5G technology matures, relying on less detachable hardware (plastic SIM) will help the design. With eSIM, mobile device manufacturers can build or embed a circuit-board directly inside the mobile device, which customers can then configure based on their needs. eSIM technology gives more control to the customers by allowing them to programme the embedded SIM to register with any mobile operator of their choice. eSIM is an evolution of the existing SIM, and there are clear benefits that make it worthwhile. However, there may also be some limitations; for example, if your eSIM enabled phone stops working, you can’t just pull the SIM out and insert it into any other phone straightaway. There are two key players for eSIM; the first one, of course, the device manufacturers, but then we also have the mobile operators who need to build capabilities in their systems to generate a QR code for customers so they can register on their mobile networks. As a result, when the overall technology matures, we may see devices with eSIM being the only option (no physical SIM), and the operators may be able to deliver eSIMs remotely and mostly online without having to give a physical eSIM pack with a QR code. At the moment, the process is not there yet and still evolving.

What are the benefits of eSIM?

eSIM makes it easier for customers to switch from one mobile operator to another. Also, if a customer wants two lines, one as their primary line and the other as a backup, they can keep both profiles on the phone and switch as and when needed. Many new smartphones are using eSIM technology to provide an ‘additional’ SIM, so basically, they have a slot for a regular physical SIM and one built-in eSIM option so you can have two SIMs in one phone, essentially making your phone a dual SIM phone.

The benefit of eSIM for device manufacturers is that having an eSIM in a device saves space which they can use for adding other features to the device. However, that benefit may only apply to those devices that are using eSIM as a replacement for the physical SIM. It may not be relevant when manufacturers are using eSIM as an additional SIM together with a physical SIM. The dual-SIM manufacturers can benefit from eSIM by keeping one plastic SIM and one eSIM.

The benefits of the eSIM technology go beyond mobile phones as it can help all mobile-connected devices, including wearables, e.g. smartwatches. If, as a device manufacturer, you don’t need a separate slot for a SIM card, you are in a better position to build the device in a smarter way. If you have ever used a smartwatch with a physical SIM before, then you can imagine how much smarter the watch would be if it were using an eSIM instead. It is important to note that the specification for eSIM has been done by GSMA (GSM Association). You can read more about eSIM on their website.

How do you get an eSIM?

If you are looking for an eSIM today, in the UK at least, you receive an ‘eSIM pack’ from your mobile operator. The eSIM pack has a QR code on it which is like a barcode. When you start the setup process, it allows you to scan the QR code, which then creates an eSIM profile on your phone for the number and operator who issued you the code. You can use your QR code more than once if you need it for any reason, e.g. if you accidentally delete the profile.

There may be a limit on the number of times you can do that, though. However, you can only use one QR code on one mobile phone. When you use your code on one phone, it gets locked to that phone. If you then decide to change your phone, you will need to request a new eSIM pack to give you a new QR code. You then need to swap your mobile number to the new phone also. It may seem like a bit of a hassle, but it is important for security reasons to avoid any potential misuse.

In order to set things up, you will need to go into your mobile phone settings menu to start the setup process. The settings are different for Android and iPhone, and some Android phones may have slight variations also. But generally, as a guide, you should be looking for that part in the Settings menu where they ask you for the mobile network or operator information.

Once you are all set up, you can use your eSIM just like a normal SIM. You can store multiple profiles on your phone for different operators, and you can switch as needed. However, you can only use one at a time.


eSIM stands for embedded SIM, and it is the technology in smartphones, smartwatches and other cellular devices that allows you to use a digital SIM instead of a physical plastic SIM. As the name suggests, it means that a microchip that enables the SIM connectivity is embedded in the device, which can be programmed by the user to any mobile operator as long as the phone is unlocked. Both physical SIM and eSIM connect to the mobile network the same way and the only difference is that physical SIM has its own circuitry whereas eSIM programmes the built-in circuitry of the phone.

Here are some helpful downloads

Thank you for reading this post, I hope it helped you in developing a better understanding of cellular networks. Sometimes, we need some extra support, especially when preparing for a new job, studying a new topic, or maybe just buying a new phone. Whatever you are trying to do, here are some downloads that can help you:

Students & fresh graduates: If you are just starting, the complexity of the cellular industry can be a bit overwhelming. But don’t worry, I have created this FREE ebook so you can familiarise yourself with the basics like 3G, 4G etc. As a next step, check out the latest edition of the same ebook with more details on 4G & 5G networks with diagrams. You can then read Mobile Networks Made Easy, which explains the network nodes, e.g., BTS, MSC, GGSN etc.

Professionals: If you are an experienced professional but new to mobile communications, it may seem hard to compete with someone who has a decade of experience in the cellular industry. But not everyone who works in this industry is always up to date on the bigger picture and the challenges considering how quickly the industry evolves. The bigger picture comes from experience, which is why I’ve carefully put together a few slides to get you started in no time. So if you work in sales, marketing, product, project or any other area of business where you need a high-level view, Introduction to Mobile Communications can give you a quick start. Also, here are some templates to help you prepare your own slides on the product overview and product roadmap.

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