An IMEI (International Mobile station Equipment Identifier) 15 digit number used to uniquely identify a mobile device on a wireless network (GSM, HSPA/LTE…). The format currently utilized is AA-BBBBBB-CCCCCC-D:
- AA: These two digits are for the Reporting Body Identifier, indicating the GSMA approved group that allocated the TAC (Type Allocation Code).
- BBBBBB: The remainder of the TAC (FAC)
- CCCCCC: Serial sequence of the Model (SNR)
- D: Luhn check digit of the entire model or (This is an algorithm that validates the ID number)
The IMEI is hard coded into a mobile device and cannot be changed, at least not easily. When a wireless user adds their SIM card to the same device, a relationship is formed in such a way that a wireless operator can identify a subscriber by:
- IMEI (International Mobile station Identifier) – hard coded in your mobile device
- IMSI (International Mobile Subscriber Identity) – hardcoded in your SIM card
- MSISDN – (Mobile Station International Directory Number) – typically defined on your SIM Card – the number dialled to call you
Where do I find the IMEI?
Depending on the phone it may be printed on the back/bottom of the phone or printed on the SIM tray itself. The IMEI should also be able to be found using the phone menu settings or by dialling *#06# on the phone itself.
Why is IMEI important?
If your phone is lost or stolen, you contact you wireless operator and inform them as soon as possible. The operator will have the IMEI for your mobile device blacklisted, which means it cannot be used on a 2G/3G/LTE Wireless Network. This makes the device unusable on any wireless operator network.
When buying a used phone always check that the used device has not been blacklisted. The last thing you want to do is spend a lot of money to on an used phone only to find that it is blocked, making it unusable. When buying a phone on-line, always confirm that the IMEI is not blocked as a blocked phone is likely a lost or stolen phone that someone is trying to sell. Also check that the used phone is not iCloud locked as well (if you are buying a used iPhone – another topic)!
If you want to check your IMEI in Canada, use this link
The structure of the IMEI/SV are specified in 3GPP TS 23.003