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.
