A Short Overview of eSIM and SIM in IoT

Building an IoT device comes with many challenges, and the choice of the connectivity provider is a crucial task. In this context eUICC is a pivotal technology as it allows customers to add, switch, or change the IoT connectivity provider remotely. In order to have the right eUICC setup, one needs to consider the specific requirements and specifications of the IoT SIM card.  

The following provides an overview of the key criteria around the IoT SIM card when using it in combination with eUICC. Familiarize yourself with the different IoT SIM form factors, the often-used terms such as iSIM or eSIM, and the relevant SIM suppliers.    

Learn more about How to Choose the Right IoT SIM. 

  1. SIM Form Factors

    1. Significantly, the diversity of dimensions makes IoT SIMs more appropriate for different devices and modules. Choosing the right form factor relies on the size and technical specs of your device. Traditional plastic IoT SIM cards and those with eUICC capability (removable SIMs) are usually represented in the same formats:  

      • 1FF: 85.6mm × 53.98mm × 0.76 mm – mostly not used today. 

      • 2FF/(Mini-SIM): 25mm x 15mm x 0.76mm 

      • 3FF (Micro-SIM): 15mm x 12mm x 0.76mm 

      • 4FF (Nano-SIM): 12.3mm × 8.8mm × 0.67mm 

      2FF or Mini-SIM is the largest available SIM size, measuring approximately 25mm long by 15mm wide. This form factor is commonly found in large IoT/M2M devices like vehicles, vending machines, and payment points. 3FF Micro-SIM is smaller in size compared to the standard Mini-SIM and measures around 15mm long by 12mm wide and is designed to fit into medium to small IoT/M2M devices such as tablets or smart health devices. 4FF Nano-SIM is the smallest removable form factor currently available in the market. Nano SIMs are approximately 40% smaller than Micro SIMs, only 12.3mm long by 8.8mm wide, and thinner by about 15%. This form factor is ideal for small devices like trackers. 

      The SIM Chip is often referred to as MFF2, which is the abbreviation for form factor (5mm x 6mm x 1mm). The MFF2 IoT SIM Chip can be equipped with the same eUICC capabilities as discussed above. Some of the new class devices are compatible specifically with those form factors as they’re namely insensitive to vibrations and movement and can resist moisture and corrosion. This turns IoT SIM Chips into a perfect solution for such verticals as in the utility sector or for consumer electronic devices.   

      SIM Chips can be found in robust/industrial grade aimed to fit tougher conditions in terms of temperature, humidity, vibrations, and so on, and are directly soldered to PCB. They are also called QFN8 or SON-8.  

      iSIM is a relatively new SIM technology, and while often referred to as a form factor, it is much more than that. Usually, IoT iSIM is designed into the module in a SoC (System on Chip). In this case, no separate hardware is needed, which implies smaller devices, lower energy consumption, facilitated logistics, decreased costs, and reduced carbon footprint.  

      Integrated into the silicon of IoT devices, iSIM reduces the number of components, costs, and energy consumption. This enables the use of smaller connected devices and provides more space for batteries. There is a general excitement around using iSIM with LPWA, combined with technologies like NB-IoT, LTE-M and remote provisioning. This mix of technologies provides more possibilities for innovative applications and devices. 

      iSIM can be made with different levels of security:  

      • TRE (Tamper Resistant Element) The network authentication keys are protected by a hardware-based security feature, similar to a discrete SIM card, ensuring the highest level of security. 

      • TEE (Trusted Execution Environment) A segregated part of a chip or module that is typically versatile and can be accessed externally. It provides a lower level of security compared to TRE. 

      • Soft SIM In this case, IoT SIM functionality can be reached only via software, with no dedicated hardware where this functionality can be placed.   


      SIM manufacturers always keep up with innovations to provide even smaller and more light-weight products, such as WLCSP (Wafer-Level Chip-Scale Packages) and CSP (Chip-Scale Packages), that are less than 25% MFF2 area. Possessing a small chip size, the WLCSP is the next step in terms of cost, space, and energy efficiency within IoT devices. 

  2. What’s the Difference between IoT eUICC and eSIM?

    1. The term eUICC (embedded Universal Integrated Circuit Card) is very often used synonymously with eSIM, but they are not the same. While eSIM often refers to the MFF2 form factor which is soldered into the device, eUICC is about technology or capability which can be available in every SIM card format, including plastic cards.   

      In this way an eUICC-enabled SIM card, no matter which form factor we are talking about, comes with technology and software that remotely provision carriers’ profiles, without the necessity to change a physical card. eUICC provides management, downloading, enabling, disabling, and deleting MNO profiles OTA or remotely. With the regular SIM, which doesn’t comprise this technology, this would mean the card needs to be physically replaced by the other operator's SIM card.   

      Our recommendation is to check in what context the term eSIM is used, as there are always the two contexts mentioned above. This is the best way to distinguish if it is the eUICC-capable SIM card or the MFF2 SIM chip, or even both, the eUICC-capable MFF2 SIM.   

      Find more useful tips about eSIM, eUICC, and iSIM in our blog article. 

  3. Who Are the Key eUICC Players in IoT?

    1. According to Transforma Insights over 3.3 billion cellular-based IoT shipments will be carried out within the 2023-2027 period, with 1 billion of RSP-capable devices, and this number will be increasing due to the flexible environment and cost efficiency eUICC SIM cards offer. Companies such as G+D (Giesecke & Devrient) or IDEMIA provide a full set of GSMA-compliant eUICC Operating Systems (OS) that are applicable to Consumer, but also M2M and IoT use cases. There are also specialized providers in the market next to the incumbents like Kigen, Nordic eSIM, and VALID who have quickly established a vast partner network and versatile customer base with a clear focus on IoT applications.

      G+D and Thales have established themselves as incumbents in the eUICC (eSIM) enablement market. Along with IDEMIA and Kigen, they have proved strong capabilities in eUICC enablement, including eSE, eUICC and iUICC operating systems, and solutions for consumer, automotive, and IoT applications. 

      G+D (Giesecke+Devrient) is a global established provider of security services, including eUICC services for IoT. The company is based in Germany. They deployed their proprietary eSIM management platform in 2012. Their eSIM management platform AirOn360® is compliant with GSMA RSP specifications for both consumer and M2M use cases. G+D can be considered an incumbent in the SIM and eUICC market. It has enabled a significant number of Consumer eUICC-capable devices, including smartphones, smartwatches, and tablets. At the same time, it targets transportation, utilities, agriculture, and smart home solutions.  

      Thales is a French company that has a broad presence in the consumer and IoT eSIM environments and supports various eSIM-enabled industrial IoT applications. Their eUICC-enabled SIM offering is available in all form factors, both plugged-in and soldered. Thales eSIM subscription management is widely used across mobile operators, operator alliances, MVNOs, car manufacturers, and OEMs. They collaborate closely with GSMA on new specifications and provide simple deployment of eSIM subscription management platforms. Thales supports the growing eco-SIM trend, with access to eUICC technology Eco SIM, card body and packaging solutions (thalesgroup.com)   

      There are also providers like Kigen and IDEMIA that are considered specialists in the field.   

      Kigen is one of the fastest growing players in IoT eUICC. It shows high expertise in firmware, compliance, and security. The vendor offers three major solution packages: Kigen Operating System (SIM OS, eSIM OS, iSIM OS), RSP Solutions (remote SIM provisioning solution, OTA server, server hosting, server sandbox), and Connectivity Solution, including integration with partners like AT&T. It has set partnerships across the value chain and delivered industry-certified iSIM hardware and have been leading iSIM tech. Kigen's eUICC SIM cards and services are relevant to IoT deployments across sectors such as automotive, healthcare, logistics, smart cities, and more.  Find more information about the company's offerings here.     

      IDEMIA has activated over 3 million eSIMs and emphasizes its services on interoperability, compliance, and IoT enablement. IDEMIA has been offering the eSIM firmware since 2016, which enabled over 100 devices. Its eUICC technology implies suspend, resume, and eDRX for better power efficiency inbound with LTE-M along with the other cellular standards (2G, 3G, 4G). The company offers standard MFF2 (5x6mm), ultra-compact plug-in card (2x2mm), and chip scale package (CSP) with an industrial option included.    

      Further relevant providers in the field are Truphone, VALID, Oasis Smart SIM, Workz, and RedTea. Please, find more in the Counterpoint report.   

  4. What’s Ahead?

    1. As the IoT landscape continues to evolve, eUICC technology is rapidly becoming an essential component of flexible and facilitated IoT deployments. However, it remains an emerging technology, and we can only anticipate various formats, devices, and use cases that will play significant role in the near future.    

      The physical MFF2 soldered eSIM chip has been on the rise in terms of hardware adoption and it will remain so in the years to come. At the same time, the new iSIM factor is seeing growing interest in the market, and it’s likely to be a leading technology in the coming years. IoT chipset and module players like Quectel and Telit together with eSIM providers such as Kigen (especially in terms of iSIM technology) or G+D started to create composable offerings in this space.  

      Furthermore, the amount of IoT and M2M hardware that is compatible with eUICC will continue to grow, leading to decreasing costs for SIM logistics and production.  

      Explore our short guideline on eUICC-capable SIM cards in IoT.

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