IoT Glossary

What is iSIM?

An integrated SIM (iSIM), is when the SIM operating system is incorporated directly onto a device’s permanent computing hardware.

What is iSIM?

With an integrated SIM (iSIM), the SIM operating system is incorporated directly onto a device’s permanent computing hardware. Discover how this most recent advancement in IoT connectivity can result in lower device manufacturing costs, longer lifetimes, better security and streamlined IoT project management.


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What is iSIM?

A programmed SIM (subscriber identity module) contains all the information necessary for a device user to join a network, including the subscriber’s international mobile subscriber identity (IMSI), and network-specific information.

In its traditional format, the SIM is stored in a chip that is incorporated into a removable card. An increasingly popular choice for IoT projects. There’s also the option of using ‘embedded’ SIMs (eSIMs). With this, the SIM takes the form of a vacuum-sealed chip soldered onto a board within the device.

iSIM goes one step further than eSIM in terms of integration. iSIM is made possible by System on a Chip (SoC) technology which enables all the computing components of a device to be embedded onto one small piece of silicon.

Instead of residing on a dedicated chip (eSIM), the very small processor core containing SIM function is integrated directly into the device’s computing or connectivity hardware. In other words, iSIM can be embedded into the micro-controller unit (MCU) or the cellular module (modem). In either case, iSIM requires a dedicated processor for security operations (e.g a ‘secure enclave’) to maintain the integrity of encryption operations.

What are the differences between eSIMs and iSIMs?

With embedded SIM (eSIM) technology, the SIM information still resides on a dedicated chip. This chip is a lot smaller than any of the removable card SIM formats. An eSIM chip measures 6x5mm compared to 12.3×8.8mm for the smallest removable card; i.e. the Nano SIM.

iSIM reduces the space required to store SIM information even further. With this, the SIM functions are embedded directly into the SoC architecture of the main computer or connectivity chip within a device. This removes the need for a discrete SIM hardware component completely.

In IoT applications, eSIMs are deployed and managed through a type of software known as eUICC (Embedded Universal Integrated Circuit Card). This software allows a single SIM card to host multiple profiles. It also enables businesses to add, remove and manage these profiles over the air (OTA) via a network system using a method called remote SIM provisioning (RSP).

iSIM also incorporates this eUICC functionality (i.e. multiple profiles, remote provisioning and management). The big difference is that the computing capabilities that enable it are integrated into the silicon SoC design, rather than existing on a dedicated chip.

The benefits of iSIMs

Manufacturing costs

The iSIM design eliminates the need for either a silicon card and tray or a dedicated soldered chip within IoT devices, resulting in a lower manufacturing costs. The approach can lead to fewer steps in the assembly process, while also shortening the manufacturing supply chain. Especially where this is multiplied across hundreds or thousands of devices, cost savings can be significant.


With iSIM, all processing cores, SIM functions, memory, and input/output ports are integrated into a single SoC. With this streamlined design, power usage becomes much more efficient, which means battery life is extended. This can mean an extended lifespan for your devices, along with a lower total cost of ownership (TCO).


The encryption elements of an iSIM reside within a self-contained processor within the SoC. The potential to replace, steal or tamper with it is effectively eliminated.


Utilising eUICC, iSIM enables a device to be deployed anywhere globally. You can manage multiple SIM profiles on devices remotely, and potentially connect them to any network securely and cost-effectively. It offers the opportunity to develop ever more compact devices at lower cost, scaling up your IoT projects, while simultaneously making device management easier.

Find out more

For an expert assessment of your connectivity needs and to discover the best fit for your connectivity options, speak to Wireless Logic today.

Learn about eUICC/eSIM technology here.

Wireless Logic

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