IoT Glossary

What is ICCID?

An ICCID is a one-of-a-kind string of 18 to 22 digits that identifies a SIM card.

What is ICCID?

An ICCID (Integrated Circuit Card ID) is a one-of-a-kind string of digits that identifies a SIM card.

Here’s a closer look at the significance of the ICCID for IoT device management, how it differs from other important cellular identifiers (IMSI, IMEI and MSISDN), and how the development of eSIM has ushered in a new identifier – the eUICCID or eID.

What is an ICCID?

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.

What do the numbers in ICCIDs mean?

The ICCID is presented as a single long sequence of digits. However, the number actually comprises four different elements. These are as follows:

Major Industry Identifier (MII)

For both mobile and IoT SIMs, the first two ICCID digits are always 89 (the MII for the telecommunications industry).

Country Code (CC)

This represents the country where the SIM card was issued (e.g. 44 for UK and 1 for the USA). Mobile Network Code (MNC). This is a string of between one and four digits, identifying the mobile network provider that issued the SIM.

Individual Account Number/Individual Identifier (II).

Each SIM’s ICCID has its own unique 13-character identifier.


The IMSI (International Mobile Subscriber Identity) is a further identifier stored on the SIM. Consisting of 15 digits, the IMSI comprises a three-digit country code, a three-digit mobile network code and a nine-digit individual identifier that’s unique to each user. As we’ve seen, the ICCID is used to identify the SIM hardware itself. An IMSI is different in that it is assigned to the user, rather than the SIM.

Mobile network providers use the IMSI to ensure that subscribers are connected to the right service. Most traditional SIM cards store a single IMSI. With a multi-IMSI solution, however, it’s possible to store multiple subscriber identities on a single SIM with a single ICCID. For vehicle trackers and other IoT devices deployed on the move, this gives you a way of swapping between networks to get the best coverage.



As we’ve seen, the ICCID is used to identify a SIM, while the IMSI is for identifying subscribers on a network. The IMEI (International Mobile Equipment Identity) number is a unique identifier for each device. (typically the cellular module inside the device). It’s made up of 15 digits: eight of which relate to device type, six relating to the device’s unique identifier, followed by a check digit at the end.

When a device seeks to make a connection, it can be checked against a worldwide IMEI database. So if one of your connected devices is lost or stolen, it’s possible to have it blocked via the IMEI, preventing it from being used with a different SIM. In IoT, a stolen SIM can be blocked if used in a different device with a different IMEI number (or range). Different IoT managed service providers have different capabilities in this area so it is worth checking with them


The IMSI is a technical code used by the network operator to identify subscribers. The MSISDN (Mobile Station Integrated Services Digital Network) is essentially the phone number for a mobile or IoT device, enabling devices to connect with each other.

Unlike the ICCID, the MSISDN does not identify the SIM itself and does not have to be stored on the SIM card. As with IMSIs, you can have multiple MSISDNs associated with the same SIM.


How does eSIM affect ICCID?

The ‘e’ in eSIM stands for embedded which creates some potential for confusion and the industry is adopting to the term Embedded SIM to differentiate from eSIM (also called eUICC). Embedded SIM  is a vacuum-sealed chip soldered directly to a board within a mobile or IoT device. eSIMs (or eUICCs) can be removable card or chip formats and have a extra memory space than traditional SIM cards, so they give you the option of having several SIM profiles and subscriptions on a single device.

eSIM also makes it much easier to manage and update your devices remotely; a process known as over-the-air (OTA) provisioning. The software that enables this OTA provisioning is known as Embedded Universal Integrated Circuit Card (eUICC). This eUICC software can also be used on traditional, removable SIM cards.

There may be multiple parties involved in producing and deploying a single eSIM solution, including device and chip manufacturers, mobile virtual network operators (MVNOs) like Wireless Logic, mobile network operators (MNOs) and subsidiary carriers responsible for creating their own SIM profiles. To avoid confusion, the industry has developed an additional classifier, the eUICCID. Each eSIM has its own unique eUICCID or eID. However, the eUICCID is not a replacement for the ICCID. An eSIM will still have its own ICCID (which is essentially the serial number for the SIM), in addition to an eUICCID, which helps manufacturers, carriers and business owners make sure that SIM profiles are remotely provisioned to the correct devices.

Find out more

Learn more about the different areas of the world of IoT here.

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