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What does the IMEI number mean?

Created by mccbleue
Technical Level : Intermediate

Summary

Details

Here on this forum, we keep seeing the same old wives' tale rearing its head suggesting that the seventh and eighth digits in the IMEI of a Nokia device indicate the country of manufacture, then list a series of countries which they claim to be represented by those digits and further claim that that some locations make poor quality products. None of this is true.

 

The location of manufacture is not encoded into the IMEI number, Nokia doesn't even create the numbers - they receive them from an external industry regulatory body. The details for all IMEIs since 1st Jan 2004 are as follows:

 

  • The first two digits (theoretically) represent the national association which issued the number, though in practice the worldwide GSM Association now issues all IMEIs. The first two digits '35' (theoretically) indicate the British Approvals Board of Telecommunications, though all IMEIs in the world currently begin 35...
  • The next six digits represent the device type (640602 is a Nokia N96, 808201 is a Nokia N82; 908801 is a Sony Ericsson K800i etc.) - this and the first two digits together are known as the Type Allocation Code (TAC).
  • The next six digits are the individual device's unique serial number
  • The final digit is a check-digit.

 

Update: A couple of people have been in touch pointing out that six digits only for the 'unique' serial number doesn't allow for devices that sell in numbers of several million - but the answer to that is simple: a device whose first eight digits are 35640602 is always an N96, but it can be that not all N96s have that IMEI series, high-volume sellers might move to a new IMEI series when one is exhausted, or the manufacturer could have different device variants using different IMEI series (such as N95-1, N95-2, N95-3...).

 

In the early days of IMEI serial numbers, back at the dawn of the mobile era, it was possible for an IMEI number to have 17 digits, the last two denoting a software version - but that format is long-since redundant as it has long been the case that a software version can be updated, even before we could update our phones ourselves.

 

This is a useful page for information on IMEI numbers:

http://www.gsm-security.net/faq/imei-international-mobile-equipment-identity-gsm.shtml

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