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What Is an IMEI Number?
An IMEI (International Mobile Equipment Identity) is a unique 15-digit number assigned to every mobile phone and cellular device. It serves as a digital fingerprint that identifies a specific device on mobile networks, regardless of which SIM card is inserted.
IMEI numbers are managed by the GSMA (GSM Association) and are essential for network operators to identify devices, block stolen phones, and manage network access. Every legitimate mobile device manufactured has a unique IMEI registered with the global IMEI database.
IMEI Structure
A standard IMEI consists of 15 digits divided into structured groups that encode specific information about the device.
- TAC (Type Allocation Code) — the first 8 digits identify the device model and manufacturer. The first 2 digits indicate the Reporting Body
- Serial Number — digits 9 through 14 are assigned by the manufacturer to uniquely identify each unit within the model
- Check Digit — the 15th digit is calculated using the Luhn algorithm to detect transcription errors
- IMEISV — a 16-digit variant that replaces the check digit with a 2-digit Software Version Number
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Перевірити номер IMEI →How IMEI Validation Works
IMEI validation uses the Luhn algorithm (the same one used for credit card numbers) to verify the check digit.
- Length check — an IMEI must contain exactly 15 digits (or 16 for IMEISV)
- Digit-only check — all characters must be numeric, no letters or special characters allowed
- Luhn checksum — starting from the rightmost digit, double every second digit, subtract 9 if the result exceeds 9, and verify the total is divisible by 10
Common Use Cases
IMEI validation serves critical purposes in telecommunications, law enforcement, and consumer protection.
- Stolen phone blocking — carriers use IMEI numbers to blacklist stolen devices, preventing them from connecting to any network
- Device verification — buyers can check an IMEI before purchasing a used phone to ensure it is not reported stolen or blacklisted
- Warranty claims — manufacturers use IMEI numbers to verify device authenticity and warranty eligibility
- Network management — carriers track device types on their network using TAC codes from IMEI numbers
IMEI vs MEID
MEID (Mobile Equipment Identifier) is the CDMA equivalent of IMEI, used by carriers like Verizon and Sprint in the US.
- MEID is 14 hexadecimal digits (56 bits), while IMEI is 15 decimal digits
- Modern CDMA devices support both MEID and IMEI for compatibility with LTE networks
- The validation algorithm for MEID uses the same Luhn formula but applied to hexadecimal values
Frequently Asked Questions
Where can I find my IMEI number?
You can find your IMEI by dialing *#06#* on your phone, checking Settings > About Phone, or looking on the device box or SIM tray. Some phones also print the IMEI on the back panel or under the battery.
Can an IMEI be changed?
Changing an IMEI is illegal in many countries because it is used to track stolen devices. While technically possible on some devices, IMEI tampering can result in criminal charges and the device being permanently blocked from networks.
Does a dual-SIM phone have two IMEI numbers?
Yes. Dual-SIM phones have two IMEI numbers — one for each SIM slot. Each IMEI independently identifies the device on the corresponding network connection.