New IMEI Protocols for GSM Handsets

From the begining of this year, a new IMEI allocation procedure has been in place. The changes relate to the format of the IMEI; the Final Assembly Code (FAC) will be obsolete and be set to 00 for the period from 01/01/2003 until 31/03/2004. A new version of the Application Form, BABT 730, Issue 5, can be downloaded from the BABT web site.

BABT is appointed by the GSM Association to allocate International Mobile Equipment Identity Numbers (IMEI) to GSM terminal equipment manufacturers for use on GSM 900 and GSM 1800 networks. The allocation procedure is funded by the GSM Association. The IMEI allocations made by BABT are confidential between the manufacturer holding the allocation, the GSM Association and BABT.

The IMEI uniquely identifies an individual mobile station and thereby provides a means for controlling access to GSM networks based on mobile station types or individual units.

The full IMEI structure is as follows:

NNXXXX YY ZZZZZZ A

Where:

TAC Type Allocation Code, formerly known as Type Approval Code = NNXXXX

NN Reporting Body Identifier, e.g. BABT

XXXX Type Identifier defined by BABT

YY This was previously a separate part of the IMEI - the Final Assembly Code (FAC).

The FAC is now obsolete and all IMEI allocations after 31/12/2002 have an 8 digit TAC. YY is set to 00 from 01/01/2003 until 31/03/2004. Setting to 00 permits the GSM industry to move to 8 digit TAC codes, but until 31/03/2004 this limits production to one million GSM terminals per TAC. Additional TAC's may be allocated to permit production of more than one million units.

ZZZZZZ Allocated by BABT but assigned to individual mobile stations by the manufacturer

A Phase 1 = 0, Phase 2 & 2+ = check digit and is defined as a function of all other IMEI digits

Since the FAC is obsolete, notification of location of manufacture is no longer required."

Posted to the site on 20th February 2003