All of our phones and many other devices need SIM cards to operate and connect to a network. The SIM card has been around for many years, but it’s changed and evolved a lot since the original SIM cards. Now, SIM cards help make the Internet of Things possible and are a part of what connects the globe. But not all SIM cards work in the same way or are the same size. Read on to learn more about key SIM card differences, particularly how SIM vs. eSIM vs. iSIM cards compare. 

What Is a SIM Card, and How Does It Work?

SIM card stands for Subscriber Identity Module and is a minuscule, plastic memory chip that slides into, or is built into, a device. It links you to a network and your phone number as well as stores crucial information about you as a cell phone user, like your minutes, texts, data usage, etc. The SIM card was invented in 1991 in Germany and was originally the size of a credit card. 

Nowadays, SIM cards are much smaller and can be found in most devices. Each SIM card has a 17-digit IMSI number that designates the country, carrier, and card. This code allows you to connect to your SIM carrier and the towers that then provide your network connection and service. 

What Are the Different Types of SIM Card? 

SIM cards have changed over the years, leaving you with several different options to choose from including traditional SIMs, iSIMs, and eSIMs. Each one meets different needs and can work well in various IoT solutions. Let’s dive into the SIM vs. eSIM vs. iSIM differences.

Traditional SIM

The traditional SIM card is the traditional removable chip found in many cell phones. Users can open up the device and insert a SIM card or remove a SIM card. Some of the pros of a traditional SIM card include convenience for many users. It’s very simple to change out your own traditional SIM. But traditional SIM cards can be less convenient for large IoT deployments. Having to physically replace each individual SIM card can be almost impossible for hundreds of devices. 

Traditional SIM cards have a few different sizes to choose from as well: 


The standard size isn’t actually the most common size, despite the name. It’s the largest SIM card at 25 x 15 mm and is used only in early generation cell phones and headsets. You’ll rarely see a SIM card in the standard size. 


A micro SIM card is 12 x 15 mm and slightly smaller than the standard one, but it’s also a mostly outdated card. Micro SIM cards have been used in phone models as recently as 2014, but most modern smartphones aren’t made with these chips anymore. 


Nano chips are the smallest at 8.8 x 12.3 mm, and they’re the most common SIM cards in devices right now. Nano cards have almost no border around the chip, so it’s not likely standard SIM cards will get smaller. Instead, SIM cards will be changed in other ways. 


The eSIM card was designed to counter the difficulty of physical access with the traditional SIM card. eSIM is an embedded SIM card or an embedded Universal Integrated Circuit Card that is installed in a device permanently. To use an eSIM device, you have to buy an eSIM compatible device and use a carrier that provides that service. You then install an eSIM profile that stores your user data. Network operators can remotely send out SIM profiles to their devices without needing physical access to switch out the cards manually. An eSIM card is also smaller than a traditional SIM, which frees up more space in the design of devices. 


An iSIM card builds off of the innovation started with eSIM cards. An eSIM is built into the device, but it’s still a separate processor within the phone. An iSIM builds the functionality of a SIM card into the device itself without a separate processor. An iSIM is designed to be energy efficient and reduce the footprint of a device. It’s also simpler for IoT deployments as well since all the profiles can be managed without access to each individual device.  


When it comes to eSIM vs. SIM cards, traditional SIM and eUICC-based SIM cards have always had more of a security concern. A card that can be accessed easily and swapped easily is also easily tampered with. The digital eSIM/iSIM were partly created to address this security concern. eSIM cards aren’t accessible in the device, which makes them more secure. 

There have also been some security concerns with the new iSIM technology. iSIM is still relatively new and hasn’t yet been certified with existing SIM accreditations. A lack of accreditation can cause some customers to worry about iSIM technology, but it’s important to note that accreditation will most likely come—the technology is just too new at this point. Until then, the best way to approach the technology is to find a good provider with high-security standards that will work to protect your devices. 

What Is a Dual SIM Card Device? 

When learning about SIM cards, you may have seen something about a dual SIM card device. These aren’t very common devices, but some companies sell devices that can hold two traditional SIM cards. These cards are inserted into the devices physically. Some devices allow you to switch which card you’re using, while others allow you to make calls on both cards at the same time. It all depends on what you’re looking for. 

People who use dual SIM card devices usually do so to keep work and personal contacts separate. You can make work calls and personal calls on just one cell phone while recording data to two different providers. 

Choosing the Right SIM Card

Using traditional SIM vs. eSIM vs iSIM cards will depend on what you need from your cards. If you have only a few devices and are looking for lots of flexibility, you might find the traditional SIM card meets your needs. Here at SIMON IoT, our traditional SIM cards are a sleek nano size that fits in modern devices. Our commercial SIM cards are flexible and easily used in any device. Our industrial cards are durable and can handle high temperatures. These traditional SIM cards meet many people’s needs. 

If you have more devices and are looking for increased security and efficiency, the eSIM card may serve your needs. If you believe you’re a candidate for eSIMs, get in touch with us. 

As iSIM technology continues to develop, you’ll find this type of technology might meet your needs. They’re the most sustainable and use the least amount of space and energy. Stay tuned for more developments in iSIM and our future iSIM technology. 

Talk to us to learn more about our SIM cards and to find the right SIM solution for you.