In order to determine which network a subscriber should be connected to, Mobile Network Operators (MNOs) use ICCID numbers. SIM cards have ICCID numbers instead of IMEI numbers, which are associated with mobile devices. Due to the fact that each SIM card is associated with an ICCID, SIM card numbers are sometimes referred to as ICCIDs. The purpose of this article is to answer the following question: What is an ICCID number and how does it work?

The first thing you need to know is what an ICCID number is and how it works. ICCIDs determine which cellular networks your device can access and what level of service you can get. Therefore, if you manufacture cellular IoT (Internet of Things) devices, you should understand what an ICCID is.

We will be discussing the following topics about ICCID in this article:

• An explanation of what each ICCID digit means.
• What your SIM’s ICCID is and how to find it.
• The ICCID is used by MNOs to identify your SIM.
• Comparing ICCIDs, IMSIs, and IMEIs.
• The impact of eSIMs on ICCIDs.

Let’s begin by taking a closer look at each set of numbers in order to gain a better understanding of what they mean.

What is the actual interpretation of the numbers that are contained within the ICCID?

Each SIM card has four sets of four digits in its ICCID number, which is an eighteen to twenty-two digit string. In order to demonstrate the use of ICCID, let’s take the example of 891004459532239470F as an example.

Each ICCID number has two digits that are always 89 in the first two digits. Using this code, you can identify this product as one for telecommunications networks.

A country code, established by the International Telecommunication Union, usually follows one to six digits. There is a country code of 1 in this example, which indicates the United States and Canada, respectively.

MNCs identify mobile network operators (MNOs) that issued SIM cards immediately after the country code. Essentially, this code represents the home network of the SIM card you are using. The MNC code for Verizon Wireless in our example is 004, which is associated with the MNC code 004.

It is important to note that each SIM has its own unique set of digits as the last set of numbers. You will not be able to find a SIM with this exact combination anywhere else in the world. SIM managers let you browse SIMs, activate or cancel services, and contact customer service for connectivity providers. This set of digits that we used in our example is 459532239470F in case you are wondering.

Where can you find the ICCID number?

ICCID numbers are vital to managing specific SIM cards, so knowing how to find them is crucial. (This is particularly important when using multiple prepaid SIM cards on the same device). I mentioned earlier that the code can be looked up on the packaging of the card, as well as on the card itself.

Despite that, it isn’t always convenient to find ICCID this way, so there is an alternative method. The ICCID number can be obtained by inserting the SIM card into a device and querying it using the device. If you are using a cell phone, you will be able to find the ICCID in the settings menu on your device. 

It is necessary to issue an AT command to an IoT device when you are connecting to it. Your device’s module will determine the exact command, but it should look something like this: 

• “AT#CCID=?” is the command for Telit modules
• “AT+CCID=?” is the command for SIMCOM modules
• “AT+QCCID=?” is the command for Quectel modules

What is the purpose of ICCID numbers for MNOs?

Any device that uses cellular connectivity searches for available networks whenever you insert a SIM card. In order to determine whether a device has access rights to the network, it uses the ICCID number and IMSI number.

Let me explain how ICCID numbers works in more detail.

An authentication request is sent from a “visiting” network to the device’s home network when it connects to a “visiting” network. In essence, the home network sends a riddle that can only be solved by the device. A random number is generated by the network using an algorithm and a shared secret key. By producing the same number, the device proves that it has the same secret key, which allows it to access the network.

If the SIM card does not have the correct key, the device cannot use the network to call emergency services. On some devices, it is even possible to use this service without the need for a SIM card. 

There is an indisputable distinction between an ICCID, an IMSI, and an IMEI.

ICCID is not the only mobile network identifier you need to know; IMSI and IMEI are also important. Your SIM card is identified by the ICCID, your subscriber by the IMSI, and your device by the IMEI.

IMSI.

An IMSI is an acronym that stands for “International Mobile Subscriber Identity” and it is a unique identifier that is assigned to each mobile subscriber. A SIM card is used to store an IMSI, much like an ICCID is used to store an ICCID. Typically, there is only one IMSI per SIM card, which corresponds to the networks that can be accessed. Multi-IMSI, on the other hand, means they store the identities of multiple subscribers simultaneously. By changing the identity of the SIM card, the SIM can be able to access more networks and choose the one with the best coverage. 

In other words, a telephone number is not the same thing as an IMSI. There are three parts to an IMSI number, each with up to 15 digits: 

• It is important to note that the first three digits of the number represent the Mobile Country Code (MCC). As a result, this can be used to determine the country of origin of the SIM card that was issued by the operator. It is always the case that the IMSI of European countries begins with the number 2.  
• A Mobile Network Code is a two or three-digit number that represents the network the user is connected to. As an example, Deutsche Telekom is represented by the number 01, for example.
• No two users share the same IMSI number, and subsequent numbers are assigned individually. 

IMEI.

Mobile radio terminals (your device) are uniquely identified by their IMEI serial numbers, which are 15 digits long. Four parts make up the report:

• Type Allocation Code (TAC) by GSMA approval group is displayed as the first two digits of the reporting body identifier. 
• A series of six digits is then followed by this number, which is referred to as the TAC number.
• After that, there are six digits that uniquely identify each device.
• The final number in equipment databases is the check digit, which is helpful in preventing errors from occurring.

IMEISVs, a term that refers to “software versions” of IMEIs, are also worth noting since they are a form of IMEI. IMEISVs are identified by their Software Version Number (SVN), which contains the last two digits.

An understanding of cellular connectivity.

There are a number of identifiers that can be applied to cellular technology. Despite the fact that they all impact connectivity, they do not necessarily have an impact on the end user. Connectivity to cellular networks makes the Internet of Things possible, enabling it to function effectively. We believe this article has assisted you gain a better understanding of ICCID numbers after reading this guide.

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