Be carefull using the IMEI. The IMEI structure has been changing. The last chab¿nged was for 1/1 2003, but there was a transition period between from 1/1 2003 to 31/3 2004.
Present structure of IMEI:
IMEI is today defined as TAC, FAC and serial number. TAC and FAC is assigned by a reporting body (Cetecom). FAC is then also partly controlled by SEMC since it’s related per production site.
New structure of IMEI:
The new structure is valid from 1/1 2003.
IMEI will be defined in the following fields
Type Allocation Code, TAC 8 digits
Each type of phone is assigned to one or several TAC depending on the number of produced units.
A major change to a type requires a new TAC assignment.
TAC is divided into two groups, NN, XXXXYY.
NN is the reporting body identifier (Cetecom)
XXXXYY is running numbers assigned per type. YY has a special meaning during the transition period.
Runs from 1/1 2003 to 31/3 2004.
During this time reporting body assigns new TAC as defined below but with YY set to 00. The running number on TAC will then be:
NN123400, NN123500, NN123600
Starting from 1/4 2004 the running numbers will be NN123400, NN123401……