Unlike embedded SIMs (aka eSIMs), iSIMs reside inside the chip. The integrated SIM moves the SIM to a secure part next to the application processor and modem. It is built as a trusted area (Tamper Resistant Element) into a System on Chip (SoC).
One of the advantages of iSIM is a full standardized embedded solution that enables interoperability across different vendors and consistent use by IoT device makers. The GSMA has released all approved GSMA iSIM specifications, integrating eUICC security while respecting SoC specificities. Today, the majority of tier-1 connectivity providers and MVNOs have also joined these efforts and have certified iSIM-based devices.
The interoperability simplifies integrating mobile connectivity into different types of connected devices. It enables operators to leverage existing eSIM ecosystems and can be applied to almost any IoT device.