Understand What IMSI is and How to Use It

International Mobile Subscriber Identity or IMSI plays a crucial role in identifying and authenticating mobile devices, SIM cards, and subscribers in a mobile network.

In this article, we will explore the IMSI definition, what it stands for, and why it's essential for mobile network identification. We will also discuss how to find IMSI on your phone and its differences with IMEI. Additionally, we will provide a step-by-step guide on how to check your phone's IMSI.

What is IMSI

The International Mobile Subscriber Identity (IMSI) is a unique identifier used in mobile networks that connect to other networks. In GSM, UMTS, and LTE networks, the IMSI is stored on the SIM card, while in CDMAOne and CDMA2000 networks, it is stored on the phone or R-UIM card. Both types of cards have been replaced by the Universal Integrated Circuit Card (UICC).

The IMSI typically consists of a 15-digit number, but can be shorter.

• The first three digits represent the Mobile Country Code (MCC).
• Mobile Network Code (MNC), which is either two digits for European standards or three digits for North American standards. The length of the MNC depends on the MCC value, and it's recommended to maintain uniformity within a given MCC area.
• The remaining digits are the Mobile Subscription Identification Number (MSIN) within the network's customer base, usually 9-10 digits long.

The IMSI conforms to the ITU E.212 numbering standard. It's important to note that IMSIs should not be confused with the ICCID, which is an identifier for the physical SIM card or virtual SIM card (if it's an eSIM). The IMSI resides as part of the profile (or one of several profiles if the SIM and operator support multi-IMSI SIMs) on the SIM/ICCID.

Read also: What is eSIM and how does it work

IMSI: why is it needed

It serves several purposes, making it a crucial component of modern mobile communication.

• Identifies the subscriber: IMSI allows the network to identify the subscriber and ensure that only authorized devices can access the network. This helps prevent unauthorized access and ensures that only legitimate users can use their SIM cards.
• Authenticates the SIM card: The IMSI helps authenticate the SIM card, ensuring that it is genuine and not tampered with. This is particularly important for mobile networks, as it helps prevent fraud and ensures that subscribers are not using fake or stolen SIM cards.
• Tracks subscriber activity: The IMSI helps track the subscriber's activity, such as location and usage patterns. This information is used by mobile operators to optimize their networks, offer targeted services, and improve customer experience.
• Facilitates roaming: IMSI enables seamless roaming between different networks, allowing subscribers to use their SIM cards when traveling abroad.
• Enhances security: IMSI helps maintain security by preventing unauthorized access to a subscriber's account and preventing SIM card cloning.

With IMSI and its role, we can better appreciate the complexities of mobile communication and the measures taken to ensure secure and efficient communication.

How does IMSI differ from IMEI

IMSI and IMEI are two distinct identifiers used in mobile communication. While they are related, they serve different purposes and have different characteristics.

IMSI (International Mobile Subscriber Identity)

• Unique identifier assigned to a SIM card
• Identifies the subscriber and authenticates the SIM card
• Used to track subscriber activity, such as location and usage patterns
• Changes when a subscriber switches SIM cards or changes their mobile operator
• Typically starts with a country code (e.g., 31001 for the USA)

IMEI (International Mobile Equipment Identity)

• Unique identifier assigned to a mobile device (e.g., phone, tablet, or modem)
• Identifies the device and its specifications
• Used to track device information, such as its serial number, model, and configuration
• Does not change when the SIM card is changed or when the device is used with a different mobile operator
• Typically starts with a country code (e.g., 01134567890123456789 for a US-made device)

Key differences:

1. Purpose: IMSI identifies the subscriber and authenticates the SIM card, while IMEI identifies the device and its specifications. 2. Scope: IMSI is specific to the SIM card, whereas IMEI is specific to the device. 3. Changeability: IMSI changes when a subscriber switches SIM cards or changes their mobile operator, while IMEI remains constant for a particular device. 4. Format: IMSI typically starts with a country code, while IMEI typically starts with a different format (e.g., 14 digits for most devices).

IMSI is used to identify and authenticate the SIM card and track subscriber activity, while IMEI is used to identify and track device information.

How to find IMSI number on your phone

To get through the IMSI check, follow these steps:

• Go to your phone's settings.
• Look for "About phone" or "Phone settings".
• Scroll down to "Status" or "SIM settings".
• Your IMSI number should be displayed next to "IMSI" or "Subscriber Identity".

IMSI is a crucial identifier in mobile communication, playing a vital role in identifying and authenticating mobile devices, SIM cards, and subscribers. Understanding what IMSI stands for and how it works can help you better appreciate the importance of security measures like VPNs. For example, Yesim VPN offers advanced security features that can help protect your personal data by encrypting your internet traffic.

Read also: TOP 8 Best eSIM Providers for Travelers in 2024: Review of Services

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