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What is an IMSI number?

IMSI stands for International Mobile Subscriber Identity. It is a string of numbers that is used by Mobile Network Operators (MNOs) to identify the subscriber element of a SIM profile. When dealing with IMSIs, it’s important to understand that this number does not identify the SIM card itself, just the user of the SIM. What’s more, IMSIs aren’t necessarily unique to a single SIM; multiple SIM cards can have the same IMSI if they’re operating over the same SIM profile.

What does an IMSI number look like?

An IMSI is made up of 14-15 digits. This long string of numbers can be separated into different sections that contain identifying information. The first 2-3 digits identify the country that the SIM is used in; this is also known as the mobile country code (MCC). The following three digits, after the MCC, are the mobile network code (MNC) identifiers. The remaining numbers are a combination of unique digits that are used to identify the subscriber.

It is also used to enable the communication between your SIM and the mobile networks. When your SIM card connects your device to a mobile network, it sends the them an IMSI number along with a secret key called a ‘Ki’. This way, the network can confirm it’s your device, allowing them to authenticate it and enable data to be traversed.

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What does multi-IMSI mean?

A multi-IMSI SIM card is exactly what it sounds like; a SIM card with multiple SIM profiles and therefore multiple IMSI numbers. Having multiple SIM profiles makes it easier for businesses to switch between carriers, which allows for a better connection and improved up-time as your devices migrate to another network when your signal drops.

For example, businesses with fleets of lorries or vans want to keep track of their vehicles at all times. By deploying single-IMSI M2M SIM cards, their trackers would only be able to connect to one specific network carrier. When these vehicles enter a remote location with limited network coverage or cross a border into another country, there is a good chance that the tracker will lose connection to the network. By replacing these SIM cards with multi-IMSI M2M SIM cards, these fleet trackers are able to connect to another carrier when their connection is poor or lost, decreasing the likelihood of any downtime.

Multi-IMSI solutions provide businesses with a lot more flexibility since they can maintain a connection with the mobile network carriers at all times. It also means that they can utilise local networks and not be subjected to pricey roaming charges when operating abroad.

What is the difference between IMSI and ICCID?

ICCID stands for integrated circuit card identification number. This forms the other part of the SIM profile and is often confused with the IMSI number. An ICCID number is usually 19 to 20 numbers long and is located on the back of the SIM card. It is used to identify each individual SIM card. For this reason, no SIMs should share an ICCID number.