What is an iSIM?

What is an integrated SIM?

Integrated SIM (iSIM) is another form factor and an alternative to traditional SIMs, while physical SIM cards are removable, placed into devices like mobile phones or IoT Devices, an iSIM is placed directly onto the device’s System-on-a-Chip, or SOC. This conserves physical space and energy, which is critical for all mobile devices, especially smaller devices like wearables and IoT sensors.

How does iSIM work?
An integrated SIM (iSIM) embeds SIM functionality directly into the device’s main system-on-a-chip (SOC). Traditional SIM cards host essential device information like subscriber identity, authentication keys, and network profiles on dedicated, removable plastic cards or embedded SIM modules. With iSIM, these essential SIM functions—storing subscriber data, managing secure authentication, and connecting securely to networks—are incorporated as a secure software layer within the SOC itself.

Inside the SOC, the iSIM relies on a built-in secure enclave, known as a Tamper Resistant Element (TRE), to store sensitive subscriber information and credentials securely. The TRE ensures encryption keys and data remain safe, resisting physical and logical attacks. When the device powers on and initiates network connectivity, the onboard SOC processor runs dedicated secure software to access the iSIM functionality stored within the TRE, authenticating the device directly with the network provider.

Provisioning and management of network data, including activating a wireless subscription and updating network profiles, occurs remotely and securely via standardized protocols called Remote SIM Provisioning (RSP). No additional hardware or physical access to the device is required, simplifying deployments at scale.

In practical terms, when a user or enterprise activates a cellular service on an iSIM-enabled device, the network operator securely downloads unique subscriber credentials and carrier settings directly onto the SOC’s secure area. This “over-the-air” provisioning process eliminates the need for specialized hardware or SIM-specific steps during manufacturing or deployment, enabling simplified and cost-effective connectivity, particularly beneficial for IoT products and embedded devices.

What’s the Difference Between eSIMs and iSIMs? 

Both embedded SIMs and integrated SIMs (iSIMs) eliminate the need for traditional, removable SIM cards, but they differ in design and implementation. An embedded SIM is a dedicated, soldered chip inside a device that functions as a programmable SIM. In contrast, an iSIM is fully integrated into the device’s SOC, eliminating the need for a separate SIM component. This key distinction allows iSIMs to reduce space usage even further while improving power efficiency.

Another difference is how they interact with a device’s security architecture. While embedded SIMs rely on separate secure elements within a device, iSIMs leverage a Tamper Resistant Element (TRE) directly within the SOC. This tighter integration enhances security by reducing attack surfaces and making it harder to tamper with SIM data. However, embedded SIMs are currently more widely adopted, as iSIM technology is still evolving.

Note: Although they are commonly confused, eSIM is a distinct concept from embedded SIM, according to the official GMSA definition. An eSIM is any type of SIM which includes eUICC technology that enables remote provisioning. eSIMs can have any form factor—they can be physical SIMs, embedded SIMs, or iSIMs.

Examples of IoT Products with iSIM Technology
iSIM technology is increasingly embedded across various IoT products and applications.
Below are some practical examples illustrating its potential use and benefits:

Wearables and fitness trackers: Fitness bands, health monitors, and smartwatches using iSIM technology benefit from smaller device profiles, improved battery life, and always-on connectivity—without needing a dedicated physical SIM. With iSIM, manufacturers produce sleeker, lighter, and more comfortable wearables suitable for everyday use.

Smart metering and utilities: Utility meters employing iSIM simplify network provisioning, securely connecting directly to cellular networks without added hardware. iSIM-enabled smart meters streamline large-scale deployments and maintenance, enhancing security and reducing operational overhead for water, gas, and electricity monitoring.

Connected medical devices: Patient monitoring equipment, remote vital-sign trackers, or glucose meters that integrate iSIM technology support continuous connectivity without bulky, externally provisioned SIM or compromised security standards. Medical device manufacturers leverage iSIM to ensure critical data is securely transmitted, using less power to extend operational lifetimes.

Asset tracking and logistics: Logistics trackers and fleet-management units integrating iSIM technology benefit from reduced costs, extended battery lives, and compact designs. With streamlined remote SIM provisioning, iSIM makes large-scale tracking deployments seamless, allowing simplified management of vehicles, containers, or valuable inventory.

Agricultural sensors and environmental monitoring: Farmers deploying IoT sensors for soil moisture, weather monitoring, crop growth tracking, or livestock health enjoy cost-effective and energy-efficient cellular connectivity enabled by iSIM technology. On-device integrated networking accelerates deployment, reduces power consumption, and ensures reliable connectivity in remote locations.

What are the Benefits of iSIM?

There are many benefits to using iSIM over traditional SIM technologies. Let’s look at just a few:

Size: Practically speaking, an iSIM is the smallest of the SIM technologies, much smaller than even an embedded SIM, which was already much smaller than a nano SIM! An iSIM is less than 1 millimeter squared. This saves space inside a device so that device manufacturers can add other components, or even make the device itself smaller as a whole, which is often cheaper to make and more appealing to customers.

Security: iSIM specifications are recognized and regulated by the Trust Connectivity Alliance, and have a consistent standard in the industry. Integrated via the SoC design, the iSIM is protected from being tampered with as it runs on a secure enclave, directly built into the chipset itself. As an iSIM cannot be removed, it’s much harder to tamper with or damage, and it also makes it more difficult for anyone to steal the phone and get away with using it themselves.

Resources: Both in terms of power consumption and cost, iSIM is a leap forward. An iSIM can be configured to reduce standby power consumption compared to designs that use a multi-chip approach like eSIM, opening doors for massive IoT. As an iSIM has fewer components and simplified design, manufacturing and logistical costs can also be heavily reduced.

Compatibility: iSIM is compatible with 2G, 3G, 4G and 5G networks, and is not tied to any specific network requirements. Its specifications have been standardized by the GSMA, as well as other global organizations that include 3GPP and ETSI. As it can be used by multiple networks at the same time, devices can switch OTA because of location, cost, or simple preference.

Use cases: Because an iSIM is so small, and because it’s so widely accepted in terms of communication standards and compatibility, the opportunities are endless for enterprises and device manufacturers to think of new and innovative business models. iSIM can be used in Utilities for electricity or gas meters, in medical equipment and wearables, for logistics use cases, in vehicle telematics systems, and beyond.

Challenges of iSIM: . Although iSIM delivers considerable advantages, several practical challenges must still be addressed:

Complex chip integration: Integrating SIM functionality directly onto the SOC introduces additional complexity during the chip design and manufacturing process. SOC providers must carefully balance securing embedded subscriber data alongside other processing functions. This complexity may extend product development timelines or increase upfront design costs.

Limited industry maturity: iSIM technology is relatively new, and the ecosystem of compatible SOC designs, carriers, and device makers is still developing. Compared to traditional SIM and embedded SIM approaches, fewer commercial solutions may currently be available, potentially limiting deployment flexibility and supplier options.

Standardization and interoperability: While GSMA and 3GPP standards cover much of iSIM’s remote provisioning and core architecture, variations might still occur during early-stage implementations. Differences between manufacturers’ security implementations or firmware approaches could cause interoperability issues or create vendor lock-in risks.

Carrier adoption and support: Not every network operator actively supports iSIM today or has the necessary infrastructure fully deployed for seamless remote provisioning. To capitalize on iSIM’s strengths, wider acceptance and unified processes among operators for activating, updating, or migrating subscriber profiles are required.

Security complexities: Despite enhanced security through the TRE, embedding the subscriber identity and sensitive keys inside an SOC combines multiple points of potential vulnerability into one chip. Ensuring robust security validation against physical, logical, and side-channel attacks becomes more critical, requiring thorough testing and specialized knowledge.

Lifecycle management: As iSIMs are not physically replaceable, lifecycle management—including changing subscriber profiles or performing secure updates and migrations remotely—must work reliably at scale. Operators and manufacturers must establish solid procedures and precautions to minimize service disruptions caused by provisioning errors or failures.

Addressing these practical challenges effectively will allow enterprises and manufacturers to successfully tap into the benefits of iSIM, ensuring wider adoption as the technology matures.

How Does floLIVE Use iSIM? 

At floLIVE, we work with our partners Kigen and Sony Semiconductors to leverage our one-of-a-kind IMSI library via iSIM, providing enterprises with compliant, multi-network local coverage for a wide range of IoT use cases.

Since one of the main purposes of iSIM is the reduction of physical size and power consumption, having a multi-IMSI capability with autonomous switching that has a low footprint and efficient power consumption is a key element in any multi-network solution. This is often not properly addressed by industry standards and other solutions in the market.

floLIVE’s multi-IMSI technology over iSIM is cost effective, has a low footprint, and ensures tight security and ultimate flexibility.

We work with all SIM factors, and our industry experience, global outlook, and customer focus put us best-placed to support the dynamic needs of a wide range of customers. We recognize that no fast-moving business can afford to be limited to just one SIM solution. That’s why we support plastic SIM, eSIM, and iSIM at the point of manufacture, as well as softSIM solutions OTA.

IoT device manufacturers and enterprises can launch, manage and scale their IoT projects worldwide, fully in line with all data privacy and compliance regulations, and with ultimate security, reliability and control.

Interested in learning more about iSIMs? Schedule a call with one of our IoT experts.