An ICCID is a unique 18 to 22-digit code used to identify a SIM (Subscriber Identity Module). You’ll sometimes see the ICCID referred to simply as the SIM Number.
The ICCID is stored inside the SIM’s processor. On physical SIM cards, it is usually also displayed on the back of the card itself (although sometimes, only the last 13 digits are visible).
Mobile network providers use the ICCID to authenticate subscribers and activate devices on their networks. The ICCID also helps businesses manage their IoT initiatives. This is because as it assigns a unique identifier for each SIM, it makes it easier to distinguish between different devices on a SIM management platform, to check the status of devices, and also it provides a reference point if you need to raise a query about a particular device with your network provider.