What Exactly is eSIM Card and Why You Might Want to Use It

Oct 08, 2020
by Arkadii Kvashuk
what is esim card

SIM cards have been around long enough for everyone to recognize them at once. In fact, you may remember more than one generation of these small pieces of plastic that connect you to the web. The progress doesn’t sleep, and the new generation known as eSim is already part of our lives and top-notch devices.  

So let’s figure out what is eSim card, what are its advantages over its predecessors, and how and where you can use it today.

Figuring Out the Acronym Soup

To understand what is an eSim in a phone we need a short guide on terminology. Most of you probably have no difficulty imagining a regular Sim card. Yet, almost nobody can say what this name actually stands for, not to mention other abbreviations used in this context. Here’s a primer:

SIM stands for subscriber identification module – the technology that verifies the user’s identity. Basically, it is your digital signature that tells your device you have the right to use the phone number. SIM is actually a tiny module held inside a PVC card most people associate with the acronym.

what is an esim and how does it work

UICC is an abbreviation you might see alongside other technical terms related to SIM cards. It stands for a universal integrated circuit card, an official name for the thing we call a SIM card.

eSim meaning is the same as that of a regular SIM, just with the word “embedded” in front. This already tells us the most significant difference – instead of being removable, eSims are built into the device. However, an e sim card is a lot more sophisticated than its predecessors, both in functionality and convenience, and opens up exciting possibilities (more on that later).

SM-DP, SM-SR, LPA – various services and protocols that enable your e sim card to connect to the network. Most of the technical stuff happens under the hood, so you have a pretty low chance of stumbling upon these terms, aside from maybe entering an activation code once.

Evolution of Sim Cards

what means esim

To understand the benefits of using eSim technology, one needs to look at how these cards changed throughout their existence. As with any novel technology, early iterations are usually clunky and cumbersome. The first SIM cards appeared in the early 1990s when the portable devices’ market was still in its infancy, so the size was not really an issue. First-gen SIM cards, or 1FF, were the size of a regular credit card.

It soon became clear that all that plastic just takes extra space, so an abridged version came along. 2FFs were only an inch long and were used in most commercial phones up to early iPhone versions. They are what most of us recognize as a regular SIM card.

As phones got smaller, so did the cards. The plastic borders were trimmed down even more in 3FF and removed entirely in 4FF. These variants, known as micro-SIM and nano-SIM, respectively, are twice smaller than regular ones.

At this point, the cards seemingly hit the bottom – the size of the connector didn’t allow it to go any smaller. So for the eSim card, it was decided to get rid of the connector entirely. This allowed eSims to become even tinier, less than a quarter of an inch. Of course, if it can qualify as a card at all – an “e sim card” is just a chip soldered directly onto a circuit board. 

What is the Benefit of eSim

The miniaturization trend seen in the previous section already reveals one of the main benefits of eSim – its size. A 5 by 6 mm chip fits much better into slim devices such as phones, tablets, smartwatches, and modems. More importantly, it allows enabling LTE data connection for other devices where using nano-SIMs is impractical. With the rise of IoT devices, an eSim card becomes indispensable for small gadgets like doorbells and sockets.

The embedded design is another eSim benefit; it is mostly relevant for hardware designers, though. Soldering the chip directly onto the board not only eliminates a bulky connector but also makes the device much more robust and less prone to malfunction. 

From the consumer standpoint, it also means fewer holes in the device, making it less susceptible to moisture and dust and more visually appealing.

While some users are concerned about not being able to remove an e sim card, it doesn’t mean that you need to be stuck with one service provider. Who would dare to refuse you the right to choose, which is now as fundamental as the right to the internet itself? An eSim card is more like an entire keychain that can store several identities, so you can activate one of the selected SIM modules without swapping an actual card. 

Of course, eSims are more expensive to manufacture, which might count towards the price of e-Sim ready devices. Nevertheless, comparing all the pros and cons of eSim makes it clear that the premium is well worth the money.

Read more: Wired Internet Connection VS Wireless: Getting Things Right

eSim vs Physical Sim

esim vs regular sim

With all of the eSim benefits listed above, it would be easy to imagine it has completely pushed earlier versions out of the market.However, it is not the case. Neither all manufacturers are eager to use this relatively expensive solution, nor all customers understand how to use an eSim embedded in the products. As long as e sim and physical cards continue to co-exist, let’s have a look at how they differ:


Modern nano-SIM cards are already small enough to fit into many portable devices like phones, tablets, portable modems, and smart gadgets. However, an e sim card is clearly superior in this regard. The small size combined with the absence of ports makes it suitable for a much broader range of applications, including:

  • Wearables
  • Home security e-sim devices
  • Smart cars
  • Logistics and transportation
  • Object tracking and monitoring
  • IoT devices
  • Industrial and agricultural smart technologies


If you are a security geek and have a basic understanding of what’s an esim, you may be suspicious about its ability to switch profiles. After all, a malicious party may be able to push their profile onto your card and essentially hijack your phone or a 4G LTE USB modem. Fortunately, this technology has a layer of protection that prevents it from happening. Essentially, a new profile can only be downloaded from your device. It would be fair to say this round is a tie.

Remote threats aside, someone can still gain access to your phone and physically remove a SIM card. This is clearly not a concern with eSim, which is hardwired into the device. This essentially means you can track the device as long as it is turned on, making theft meaningless. Not only that, it offers a higher level of protection from environmental factors by eliminating ports. This eSim vs SIM round goes to the contender.

Read more: How to Prevent Data Breaches: Rules for Safe Internet Connection


For a SIM-based device, the number of profiles is limited by the number of hardware ports it has unless you are prepared to carry your SIM cards around and switch them when needed. With an eSim-enabled phone or 4G wifi portable modem, you can change them from device settings. 

nect app

For example, using a nect MODEM, you can switch a card in just a few clicks in the app. Users who travel a lot, juggle the cards with better telecom deals, or use several corporate numbers will find it a significant quality-of-life improvement.

How to Use eSim when Traveling

how to use esim when traveling

Right now, the options for travelers are relatively modest. So far, providers have been slow adding eSim support to their services, so start by checking the one you use. If it does allow switching to eSim, start by transferring your home number to an e sim card to have your regular SIM port available just in case.

Let us note that nect MODEM has both nano sim and e-Sim options available and provides e-SiM based data plans for 113 countries and territories. So you may not worry about having to research local providers or face their frowned ‘what means eSim’ look – both eSIM and known, trusted nano-SIM are here in your modem.     

Final Thoughts

Although we’ll still have to wait before the industry catches up and we can enjoy all eSIM benefits, even in its current state, the technology helps you make your online experience easier and safer. The embedded SIM technology is clearly superior to regular SIM cards, and we are happy it makes part of our innovative portable modem. 

All illustrations are created by Lucy Ivanova, a Chief Creative Officer at nect.