Difference between IMSI and ICCID numbers

Mobile cellular networks and devices have many ways to identify the mobile device user, and IMSI and ICCID are some of those identification numbers. Both IMSI and ICCID numbers are associated with the SIM card inside a cell phone or any cellular device. This post aims to outline the difference between these two numbers.

IMSI is the network identity of the SIM

IMSI stands for International Mobile Subscriber Identity, and it is a unique number assigned to each SIM card. IMSI is a 15 digit number that can identify the user of the SIM within a mobile network. Mobile networks keep the IMSI secure and do not communicate this number. Instead, a mobile network generates a temporary subscriber identity for the SIM called TMSI or Temporary Mobile Subscriber Identity, used for most communication. The fifteen digits in the IMSI number represent the different parts of the subscriber identification. The first three digits in the IMSI are for the country code or MCC (Mobile Country Code). For example, 234 is the mobile county code for the UK. The next two digits in the IMSI are the Mobile Network Code or MNC, which identifies the mobile network operator. For example, 15 is the mobile network code for Vodafone UK. Finally, the last ten digits of the IMSI represent the Mobile Subscriber Identification Number (MSIN). MSIN is for identifying the subscriber within the mobile network or Public Land Mobile Network (PLMN). Mobile operators use the IMSI number of a mobile subscriber to assign and manage any services allocated to that particular subscriber. IMSI is linked to the subscription of the SIM in the network as opposed to the SIM hardware.

ICCID is the hardware identity of the SIM

ICCID stands for Integrated Circuit Card Identifier, and it is a number assigned to the SIM hardware, i.e. the chip of a SIM card. A SIM card is a circuit board, and ICCID is a 19 or 20 digit unique number assigned to the SIM circuitry. It means that ICCID is the primary ID of the SIM and not the mobile phone number. If you lose or damage your SIM card, it is possible to get another physical SIM with a new ICCID and ask your mobile operator to assign your previous phone number to the new SIM. Nowadays, some mobile devices also have embedded SIM cards or eSIM where the circuitry for the SIM is built directly on the mobile device. The ICCID number is printed at the back of the SIM in plastic or physical SIM cards, but you can use your phone to read the ICCID number. Generally, if you go to your phone settings, the “About” or “About Phone” option can help you locate your ICCID number. For example, if you have an iPhone, you can go to “Settings”, “General”, and then “About” to find the ICCID number. For Android phones, it may depend on the phone manufacturer, but if you go to “Settings” and “About Phone”, you should be able to find it. You must have your SIM card inside the phone to find the ICCID number, and if the SIM is taken out, you won’t see the ICCID number any longer. If you have a dual-SIM phone, you will have two separate ICCID numbers, one for each SIM.


IMSI stands for International Mobile Subscriber Identity, and it is a 15 digit unique number assigned to each SIM card. IMSI allows a mobile network to identify a mobile user to assign and manage services that a subscriber is entitled to. ICCID stands for Integrated Circuit Card Identifier, and it is a 19 or 20 digit unique number assigned to the SIM hardware, i.e. the circuit.

Here are some helpful downloads

Thank you for reading this post, I hope it helped you in developing a better understanding of cellular networks. Sometimes, we need some extra support especially when preparing for a new job, or studying a new topic, or maybe just buying a new phone. Whatever you are trying to do, here are some downloads that can help you:

Students & fresh graduates: If you are just starting, the complexity of the cellular industry can be a bit overwhelming. But don’t worry, I have created this FREE ebook so you can familiarise yourself with the basics like 3G, 4G etc. As a next step, check out the latest edition of the same ebook with more details on 4G & 5G networks with diagrams. You can then read Mobile Networks Made Easy which explains the network nodes e.g. BTS, MSC, GGSN etc.

Professionals: If you are an experienced professional but new to mobile communications, it may seem hard to compete with someone who has a decade of experience in the cellular industry. But not everyone who works in this industry is always up to date on the bigger picture and the challenges considering how quickly the industry evolves. The bigger picture comes from experience which is why I’ve carefully put together a few slides to get you started in no time. So if work in sales, marketing, product, project or any other area of business where you need a high-level view, Introduction to Mobile Communications can give you a quick start. Also, here are some templates to help you prepare your own slides on product overview and product roadmap.

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