What Is International Mobile Equipment Identity?
International Mobile Equipment Identity (IMEI) is a unique, 15-digit serial number that serves as a global identifier for a mobile device within the realm of mobile network technology. It is a critical component in ensuring the integrity and security of wireless communication and falls under the broader category of Mobile Device Technology. Unlike a phone number, which identifies the subscriber, the IMEI identifies the device itself, making it an essential tool for device identification and various management functions by network operators.
History and Origin
The concept of the International Mobile Equipment Identity arose from the need to uniquely identify mobile phones within GSM networks to combat theft and enable effective network management. The GSM Association (GSMA), a global organization representing the interests of mobile operators worldwide, plays a central role in allocating and managing IMEI numbers. The structure and allocation of IMEI are governed by standards set by organizations like the 3GPP (3rd Generation Partnership Project).
A significant development in the application of the IMEI came with the establishment of stolen phone databases. In 2012, the Federal Communications Commission (FCC) and major U.S. wireless carriers collaborated to create such a database, aiming to deter smartphone theft by rendering reported stolen phones unusable on cellular networks. This initiative sought to make stolen devices less valuable, even if a thief attempted to use a different subscriber identity module.32
Key Takeaways
- The International Mobile Equipment Identity (IMEI) is a unique 15-digit serial number assigned to every mobile phone.
- Its primary function is to identify the specific device, not the user or the subscriber account.
- IMEI is crucial for fraud prevention by allowing mobile networks to block lost or stolen devices.
- The GSMA is responsible for allocating and managing IMEI numbers globally through its central database.
- IMEI alteration, while technically possible, is often illegal and does not guarantee enhanced privacy due to other device identifiers.
Formula and Calculation
The International Mobile Equipment Identity (IMEI) is a 15-digit decimal number structured to convey specific information about the device. While not a "formula" in the financial sense, its components are systematically arranged:
AA-BBBBBB-CCCCCC-D
Where:
AA-BBBBBB: This initial eight-digit portion is known as the Type Allocation Code (TAC). It identifies the device's manufacturer and model. The GSMA allocates these TACs to manufacturers.31CCCCCC: These six digits represent the manufacturer-defined unique serial number for that specific device model.30D: The final digit is a check digit, calculated using the Luhn algorithm. This digit helps verify the integrity of the IMEI.29
The Luhn formula for calculating the check digit involves a checksum algorithm:
Where (d_i) is the (i)-th digit of the first 14 digits of the IMEI. If doubling a digit results in a number greater than 9, you sum its digits (e.g., (2 \times 7 = 14 \rightarrow 1+4=5)). The sum is then found, and the check digit is the smallest digit that when added to the sum makes it a multiple of 10.
Interpreting the International Mobile Equipment Identity
The International Mobile Equipment Identity serves as a distinct digital fingerprint for a mobile device. When a device connects to a mobile network, its IMEI is transmitted and used by network operators for identification and authentication purposes.28 This unique identifier is stored in a database called the Equipment Identity Register (EIR), which contains information about authorized mobile phone equipment.27
Interpretation of the IMEI focuses on its ability to confirm a device's identity and status. It reveals details such as the brand and model of the phone without needing physical access to the device.26 Crucially, the IMEI helps determine if a device has been reported as lost, stolen, or is otherwise unsuitable for network access. If an IMEI is listed on a "blacklist," network operators can deny service to that device, rendering it unusable for calls, texts, or data, even if the subscriber identity module (SIM card) is changed.25
Hypothetical Example
Consider a situation where an individual, Sarah, has her smartphone stolen. Upon realizing the theft, Sarah immediately contacts her mobile service provider and the police. She provides them with the International Mobile Equipment Identity (IMEI) of her stolen phone, which she had previously noted down or retrieved from the phone's packaging.
Her mobile operator then adds this IMEI to a global blacklist maintained by the GSMA. This action ensures that even if the thief attempts to insert a new subscriber identity module into the stolen device, it will be recognized by mobile networks as a blacklisted device. As a result, the phone will be unable to connect to any network for calls, messages, or data, significantly reducing its utility and resale value for the thief. This process underscores the critical role of the IMEI in deterring mobile phone theft and enhancing overall data security.
Practical Applications
The International Mobile Equipment Identity has several vital practical applications in the mobile ecosystem, extending beyond mere device identification:
- Theft Deterrence and Recovery: Perhaps the most significant application is its role in combating mobile phone theft. When a device is reported lost or stolen, its IMEI can be added to a global blacklist.23, 24 This prevents the device from accessing mobile network services, effectively rendering it useless to a thief, even if they replace the subscriber identity module.22 Consumers can also use online tools to check if a used phone they intend to purchase has been reported stolen by entering its IMEI.21
- Network Management: Network operators utilize the IMEI for various asset management and analytical purposes. It allows them to understand the types of mobile devices connected to their network, monitor usage patterns, and manage device-specific services.20
- Insurance Claims and Warranty: Insurance companies often require the IMEI when processing claims for lost or stolen phones, as it provides a unique identifier for the specific insured device. Similarly, manufacturers use the IMEI for warranty verification.
- Device Unlocking and Trade-ins: When unlocking a phone from a particular carrier or trading in a used device, the IMEI is frequently required to verify the device's status and history. The U.S. wireless industry, through organizations like CTIA, has actively promoted consumer tools for checking device status using IMEI to prevent the resale of stolen phones.19
Limitations and Criticisms
Despite its utility in device identification and fraud prevention, the International Mobile Equipment Identity is not without its limitations and has faced criticism, particularly concerning privacy and potential misuse.
One significant concern revolves around the ability to alter or "spoof" an IMEI. While generally illegal in many jurisdictions, specialized tools and software exist that can modify a device's IMEI.18 Such alteration can allow stolen phones to bypass blacklists and reconnect to networks, undermining the effectiveness of theft deterrence measures. Furthermore, attempts at IMEI randomization or frequent changes to enhance privacy are largely ineffective and can even draw unwanted attention from network operators who detect inconsistencies between the IMEI and other device identifiers.17 Security experts note that unless the physical chipset itself is custom-built, changing the IMEI is not a strong data security feature.16
Another criticism pertains to privacy implications. The IMEI, as a persistent identifier tied to a mobile device, can contribute to an individual's digital footprint. Law enforcement and intelligence agencies have reportedly used IMEI numbers for tracking devices, raising concerns about surveillance and the potential for unauthorized monitoring.14, 15 While the IMEI identifies the device and not the user directly, when combined with other data, it can contribute to a comprehensive profile of an individual's movements and activity. Academic research highlights the vulnerabilities associated with IMEI manipulation and its impact on privacy and security.13
International Mobile Equipment Identity vs. Subscriber Identity Module
While both the International Mobile Equipment Identity (IMEI) and the subscriber identity module (SIM) are crucial components of a mobile device, they serve distinct purposes and identify different elements of the mobile communication ecosystem.
The IMEI is a unique serial number that identifies the physical hardware of the mobile phone itself. It is hard-coded into the device and remains with the phone regardless of who owns it or what network it's connected to. The IMEI is analogous to a vehicle identification number (VIN) for a car. Its primary function is to authenticate the device on a mobile network and is instrumental in preventing the use of stolen phones by enabling remote blocking.12
In contrast, the SIM card is a small, removable chip that stores subscriber-specific information, such as the International Mobile Subscriber Identity (IMSI) number, phone number, and network authorization details.11 The SIM card identifies the user and their account to the mobile network, enabling services like calls, texts, and mobile data transfer. If you switch phones, you typically move your SIM card to the new device to retain your phone number and service. Therefore, the IMEI identifies what device is being used, while the SIM identifies who is using the device.
FAQs
How can I find my phone's IMEI?
You can typically find your International Mobile Equipment Identity by dialing *#06# on your phone's dial pad. It may also be located in your phone's settings menu (usually under "About Phone" or "Status"), on the original packaging, or on a sticker under the battery (for phones with removable batteries).10
Can an IMEI be changed?
Technically, an International Mobile Equipment Identity can sometimes be altered using specialized tools, but this practice is generally illegal in many countries and can have severe consequences, including rendering the device permanently unusable on legitimate mobile networks.8, 9 It also does not reliably enhance privacy.7
What happens if an IMEI is blacklisted?
If an International Mobile Equipment Identity is blacklisted, it means the mobile device has been reported as lost or stolen and is typically blocked from connecting to cellular networks for calls, texts, or data security. This renders the phone largely unusable on those networks, even if a new subscriber identity module is inserted.5, 6
Is the IMEI linked to my personal data?
The International Mobile Equipment Identity identifies the mobile device itself, not the user or their personal data. It does not contain information like your name, address, or phone number.3, 4 Your personal information is primarily linked to your subscriber identity module (SIM card) and the account associated with it. However, when combined with other network data, IMEI can contribute to device tracking.2
Why should I know my IMEI?
Knowing your International Mobile Equipment Identity is crucial for fraud prevention and for protecting your mobile device. In case of theft or loss, providing your IMEI to your network operators and law enforcement enables them to blacklist the device, making it unusable on their network and reducing its value to thieves. It's also often required for insurance claims or when checking the status of a used phone purchase.1