What Is iSIM? The Next Step After eSIM

iSIM (integrated SIM) takes the SIM function one step further than eSIM: instead of a discrete eUICC chip soldered to the motherboard, the SIM’s secure element is built directly into the device’s SoC (System-on-Chip). The result is no separate SIM component at all — subscriber authentication is handled inside the main processor package. Like eSIM, iSIM uses GSMA remote provisioning, so carrier profiles are downloaded over the air rather than delivered on a physical card.

Key points:

• iSIM eliminates the separate eUICC chip by integrating the secure element into the SoC.
• The remote provisioning protocol (GSMA SGP.22 for consumer devices, SGP.32 for IoT) is the same as eSIM — carriers issue profiles the same way.
• iSIM is in early commercial deployment as of mid-2026, primarily in IoT and select smartphone chipsets.
• For everyday consumers, eSIM is the practical technology today; iSIM becomes relevant when evaluating wearables, IoT modules, and next-generation chipset designs.

For background on how eSIM works before reading this article, see What Is an eSIM?.

The SIM Evolution: From Physical Card to Integrated Silicon

To understand where iSIM fits, it helps to trace the SIM’s hardware evolution.

The original SIM was a full-size removable card (1FF, defined in ETSI GSM 11.11) containing a dedicated integrated circuit that stored the IMSI, authentication key (Ki), and network credentials — for a detailed look at how a SIM card works, see What Is a SIM Card?. Over time, the card shrank through Mini-SIM (2FF), Micro-SIM (3FF), and Nano-SIM (4FF) — each change reduced the card area while keeping the same contact interface.

eSIM (embedded SIM) removed the removable form factor entirely. An eUICC (embedded Universal Integrated Circuit Card) chip is soldered to the device motherboard and loaded with carrier profiles remotely, following the GSMA SGP.22 standard for consumer devices. The credential store moved off the swappable card and onto a chip that is permanently part of the device.

iSIM continues this trajectory by eliminating even that discrete chip. Instead of an eUICC soldered alongside the application processor, iSIM places the secure element function inside the SoC itself — in a hardware-isolated partition called a secure enclave or Trusted Execution Environment (TEE). The result is that the SIM function is no longer a separate component on the PCB.

This progression — removable card → soldered discrete chip → integrated into SoC — reflects the sustained industry pressure to reduce device size, component count, and power consumption, especially for IoT and wearable applications.

How iSIM Works: The Hardware Architecture

The Secure Element Inside the SoC

A traditional eSIM uses a separate eUICC chip that communicates with the application processor over an ISO/IEC 7816 or SPI interface. The eUICC contains its own secure memory, cryptographic coprocessor, and operating environment, isolated from the main processor.

iSIM moves this secure element inside the SoC boundary. The SoC vendor (Qualcomm, MediaTek, Samsung LSI, or others) integrates a hardware-isolated security domain — sometimes referred to as an iSIM partition — within the same silicon package as the application processor and modem. This partition has:

• Dedicated secure storage for IMSI, Ki, and carrier profiles
• A cryptographic processor for authentication computations
• Hardware isolation from the rest of the SoC, preventing unauthorized access by the application processor or operating system

From the network’s perspective, iSIM authenticates identically to a traditional UICC or eUICC. The 3GPP authentication algorithms (MILENAGE, TUAK) run inside the secure partition; the resulting authentication vectors are passed to the modem. The carrier’s network sees no difference.

Remote Provisioning

iSIM retains the remote provisioning model that eSIM introduced. Carrier profiles — containing credentials, network configuration, and IMSI — are downloaded from an SM-DP+ server (Subscription Manager Data Preparation, defined in GSMA SGP.22) for consumer devices, or managed by an eIM (eSIM IoT Remote Manager) for IoT devices following GSMA SGP.32.

Profile download and management follow the same GSMA-defined procedures as eSIM:

• For consumer devices: QR code scan, activation code entry, or carrier app
• For IoT devices (SGP.32): server-initiated push via eIM, without requiring user interaction

Multiple carrier profiles can be stored within the SoC’s secure element. Profile switching is handled the same way as eSIM — through the device’s settings interface on consumer devices, or through the eIM on IoT devices.

iSIM vs eSIM: What Actually Differs

Both technologies use the same GSMA remote provisioning standards and the same underlying authentication protocols. The functional difference is solely in hardware placement.

The table shows that from a subscriber perspective — how you activate, switch, and manage carrier plans — iSIM and eSIM are functionally equivalent. The difference is entirely in the hardware that implements those functions.

GSMA Specifications Governing iSIM

The GSMA maintains three eSIM specifications. Understanding which applies to iSIM depends on the device type.

SGP.22 — Consumer Devices

GSMA SGP.22 (RSP Technical Specification for Consumer Devices) defines remote provisioning for smartphones, tablets, and wearables. The GSMA publishes multiple active version branches of SGP.22; refer to the GSMA website for the current release.

SGP.22 governs the SM-DP+ provisioning server, the LPA (Local Profile Assistant) on the device, and the profile download and management procedures. iSIM implementations on consumer devices — where the secure element is in the SoC — operate under the same SGP.22 procedures as conventional eSIM. The specification does not mandate a specific hardware form; it defines the software and protocol interfaces.

SGP.32 — IoT Devices

GSMA SGP.32 v1.0, published May 2023, is specifically designed for constrained IoT devices — sensors, trackers, meters — that typically lack a user interface. The key architectural difference from SGP.22 is that SGP.32 uses an eIM (eSIM IoT Remote Manager) for server-initiated profile management: the eIM can push profile changes to the device without user interaction.

SGP.32 is particularly relevant to iSIM because the primary commercial driver for iSIM integration has been IoT. Devices using Qualcomm’s Snapdragon X35, for example, combine LTE-M/NB-IoT connectivity with an integrated iSIM and are positioned for IoT deployments where an external SIM chip would be too large, too power-hungry, or too costly.

SGP.02 — Machine-to-Machine (M2M)

SGP.02 is the earlier M2M specification, predating consumer eSIM. It uses a push-based provisioning model managed by an SM-SR (Subscription Manager Secure Routing). SGP.32 is the successor specification for IoT devices; new designs typically target SGP.32 rather than SGP.02.

Benefits of iSIM

Board Space Reduction

Removing the discrete eUICC chip frees PCB area. For a smartphone, the gain is relatively modest — eUICC chips are small. For IoT devices — particularly wearables, medical sensors, and miniaturized trackers where every square millimeter matters — eliminating an external component can be the difference between a feasible design and one that does not fit within physical constraints.

Power Efficiency

A discrete eUICC chip requires its own power supply circuitry and draws standby current independently. Integrating the SIM function into the SoC allows the SIM’s power state to be managed alongside other SoC subsystems, enabling more coordinated power gating. In battery-constrained IoT devices — especially those targeting multi-year battery life — this is a meaningful efficiency gain.

Reduced Component Count and Supply Chain Complexity

Every discrete component added to a device introduces procurement risk, assembly steps, and potential failure points. Integrating iSIM into the SoC removes one vendor, one component, and one solder joint from the BOM. For high-volume IoT deployments this simplification has manufacturing and logistics value.

Same Security Model

iSIM does not reduce security by integrating the secure element into the SoC. The SoC vendor implements hardware isolation — verified through industry certification programs such as GlobalPlatform TEE and Common Criteria EAL — to ensure that the iSIM partition cannot be accessed by the application processor or operating system. The cryptographic operations and credential storage remain isolated even though they share the same silicon package.

Current Adoption Status

iSIM has moved from research and prototype stages into early commercial chipset integration. Adoption is concentrated in IoT modules and wearable-class SoCs rather than flagship consumer smartphones, reflecting where the space and power benefits are greatest relative to the cost of integration.

Chipsets with Integrated iSIM

iSIM integration in commercially available chipsets is in early deployment as of mid-2026. Verified examples include:

• Qualcomm + Thales GSMA-compliant iSIM (announced MWC February 2023): built on a modified Snapdragon 8 Gen 2 variant — a reference/early-commercial platform demonstrating on-SoC iSIM, not a standard shipping consumer SKU.
• Qualcomm Snapdragon X35 5G Modem-RF System (announced MWC February 2023): targets LTE-M/NB-IoT IoT applications; reported to include iSIM capability in conjunction with the modem subsystem.
• Arm Kigen iSIM: Arm’s dedicated iSIM IP family, targeting IoT and wearable SoC designs; licensable by chipset vendors for integration into their own SoCs.
• Galaxy Watch4 / Watch5: use eSIM via a discrete eUICC chip — not an on-SoC iSIM. The Exynos W920 SoC in these devices does not integrate iSIM.

Mainstream consumer smartphone SoCs — Qualcomm Snapdragon 8 Gen series, Apple A-series, Samsung Exynos flagship — as of mid-2026 continue to use a discrete eUICC chip for eSIM rather than an on-SoC iSIM integration. The transition to iSIM in flagship smartphones has not yet reached broad commercial availability.

IoT as the Primary Adoption Driver

The earliest and most consistent deployment of iSIM has been in IoT and wearable segments, where the space and power arguments are strongest. Industrial IoT, cellular-connected wearables, asset tracking, and smart metering are the primary application areas where iSIM’s component-reduction advantage is most relevant.

Carrier and Ecosystem Support

Carriers that have deployed GSMA SGP.22 provisioning infrastructure for eSIM can support iSIM on consumer devices without additional carrier-side changes. For IoT deployments using SGP.32, carriers and connectivity platform providers must support the eIM interface. The remote provisioning protocol is the same; the change is on the device hardware side.

For IoT connectivity at scale, some enterprises use connectivity management platforms (from providers such as Emnify, Eseye, or Tele2 IoT) that sit between the carrier and the device fleet, managing profile assignment and switching across multiple carrier agreements. These platforms must support the SGP.32 eIM interface to manage iSIM-equipped IoT devices. The underlying GSMA standard defines the interface; platform support varies by vendor.

Limitations and Considerations

Limited Consumer Device Availability

As of mid-2026, iSIM is not yet available in mainstream consumer smartphones from Apple, Samsung (flagship Android), or Google (Pixel). Users evaluating iSIM as a consumer technology will find eSIM far more widely supported across the current device market. For device compatibility information, see eSIM-Compatible Devices.

SoC Vendor Dependency

With eSIM, the eUICC chip vendor is separate from the SoC vendor. Manufacturers can select a preferred eUICC supplier (Infineon, ST, NXP, and others) and change suppliers independently of the SoC. With iSIM, the secure element is part of the SoC, making the SIM capability dependent on the SoC vendor’s implementation and certification. This reduces design flexibility.

Re-issue Logistics on Device Failure

Because iSIM is inside the SoC — which is part of the device motherboard — device failure or damage means the SIM function is inaccessible along with the rest of the hardware. This is the same situation as eSIM: carriers must re-issue the profile to a replacement device. There is no physical SIM card to extract.

Certification and Compliance

SoC-integrated secure elements must obtain relevant security certifications (GlobalPlatform, Common Criteria) to be accepted by carriers and regulators. The certification process for iSIM is analogous to eUICC certification for eSIM, but it must be conducted for each SoC design where iSIM is integrated. This adds cost and time to chipset development.

The GSMA also maintains a Security Accreditation Scheme (SAS) for remote provisioning infrastructure. Both the device-side secure element and the carrier-side SM-DP+ (or eIM for SGP.32) must meet defined security requirements. These requirements apply equally to eSIM and iSIM deployments.

iSIM and IoT: The Core Use Case

The GSMA SGP.32 specification, published in May 2023, was developed specifically in response to the needs of IoT device manufacturers. SGP.32 differs from the consumer eSIM specification (SGP.22) in a critical way: it does not require user interaction for profile management.

In a consumer eSIM setup, the user scans a QR code or taps through a carrier app. An IoT sensor embedded in agricultural equipment or a utility meter has no screen and no user. SGP.32 addresses this with the eIM (eSIM IoT Remote Manager), which manages profile operations — download, enable, disable, delete — from the server side, without requiring any interaction at the device.

iSIM’s hardware characteristics align with SGP.32’s use case: IoT devices benefit from reduced component count, low power draw, and small form factor. The combination of iSIM hardware and SGP.32 provisioning is positioned as the basis for large-scale cellular IoT deployments where deploying and managing SIMs manually would be operationally infeasible.

SGP.32 also supports constrained network environments. Unlike SGP.22, which is designed for devices with stable broadband connectivity, SGP.32 includes support for CoAP over UDP with DTLS — lightweight protocols suitable for NB-IoT and LTE-M networks where bandwidth and packet size are restricted. This makes iSIM with SGP.32 suitable for devices that communicate intermittently over low-bandwidth cellular links.

How iSIM Relates to Frequency Bands and Network Access

iSIM does not change which frequency bands a device supports. Band support is determined by the modem and RF front end, not by the SIM or iSIM. A device with an iSIM accesses the same LTE, 5G NR, NB-IoT, or LTE-M frequencies as a device with a conventional SIM, provided the modem supports those bands.

One area where integration matters: when iSIM is combined with the modem in the same SoC package — as in Qualcomm’s X35 design — the modem and SIM can share a more tightly integrated power management scheme. This does not affect which bands are supported, but it can reduce the overall power budget for the connectivity subsystem.

For background on how frequency bands affect coverage and roaming, see Frequency Bands Explained.

One important note for roaming: iSIM devices use the same roaming authentication procedures as devices with physical SIM or eSIM. Band support determines which networks are accessible; the SIM technology (iSIM, eSIM, or physical) does not affect roaming eligibility.

Summary: Physical SIM vs eSIM vs iSIM — and How to Choose

For a practical side-by-side comparison of physical SIM and eSIM — including which to choose for travel, flexibility, and everyday use — see Physical SIM vs eSIM: Differences and How to Choose.

iSIM is not a new provisioning standard — it reuses the GSMA remote SIM provisioning infrastructure that carriers have already built for eSIM. What changes is the hardware: the secure element moves into the SoC, removing a discrete component and enabling smaller, lower-power designs.

For users comparing plans on current devices, eSIM is the relevant technology. iSIM becomes the practical consideration when evaluating IoT module specifications, wearables, or next-generation chipsets. Use SimFinder to search and filter plans by eSIM support across multiple countries.

Related Guides

• What Is an eSIM? — How eUICC works, the SGP.22 standard, and which devices support eSIM
• Physical SIM vs eSIM: Differences and How to Choose — Side-by-side comparison and a use-case decision framework
• eSIM-Compatible Devices — Which iPhones, Android phones, and tablets support eSIM
• What Is a SIM Card? — IMSI, Ki, UICC form factors, and the shift from physical SIM to eSIM
• Frequency Bands Explained — How LTE and 5G frequency bands affect coverage, speed, and roaming