The International Mobile Equipment Identity (IMEI) is used to identify TD-SCDMA, WCDMA, and GSM mobile terminal equipment. An IMEI consists of 15 decimal digits ranging from 0 to 9, and is divided into three components: TAC (Type Allocation Code), serial number, and check bit. According to the provisions of the International 3GPP organization (Third Generation Partnership Program), the IMEI of global mobile terminals is uniformly issued and managed by the GSMA(Global System for Mobile Communications Association). At present, the IMEI auditor designated by the GSMA is responsible for the issuance and management of TACs. Since 2008, the Telecommunications Terminal Industry Association (TAF) has agreed with the GSMA to obtain the authority to administer TAC issuance in China. Tacs issued by TAF have the same effect as those issued by other audit bodies (BABT, India MSAI, North America CTIA, etc.). In order to ensure the smooth review of domestic mobile communication terminal numbers, this document is formulated.
Scope of application
In accordance with the GSMA IMEI Review Process Procedure Document (TS.06), the TAC must be applied for by the brand owner. Submit TAC application to TAF, and TAF is responsible for the enterprise TAC account registration and the approval of TAC application and payment. TAC application fees will be collected by GSMA China Audit Agency TAF.
Attachment: IMEI International Mobile Equipment Identity (IMEI) is the international Mobile Equipment Identification Code, used to identify TD-SCDMA, WCDMA, and GSM mobile terminal equipment. Each mobile terminal has a unique device identification code in the world.
IMEI consists of 15 decimal digits ranging from 0 to 9. According to the international standard of IMEI, IMEI can be divided into three parts: TAC (Type Allocation Code), serial number and check digit. The numbering format is as follows:
Number format of an IMEI
IMEI (15 decimal digits)
TAC - Model assignment code (8-bit) Serial number (6-bit) Check bit (1-bit) NNXXXXXX ZZZZZZ A
1. Composition and meaning of TAC
As shown in the figure above, TACs are composed of 8 digits, and in fact, all IMEI audit bodies currently issue and manage TACs. The first two NN digits of a TAC are the ID of an approving authority. Different numbers represent different TAC approving authorities. At present, the identification code of the approval authority of BABT is "35", that is, the TAC starting with "35" is issued; The approval authority identification code for TAF is "86", that is, the TAC is issued beginning with "86". The next six digits (XXXXXX) after TAC are the mobile terminal model identification code defined by the approving authority.
2. Composition and meaning of serial number
The 9-14 digit "ZZZZZZ" of IMEI is the serial number of the product, representing "000000-999999" a total of 1 million numbers, and the enterprise allocates a fixed type of terminal equipment according to the actual production needs. Therefore, the TAC applied by the enterprise for each model can be used for 1 million terminals of the same model, and when the output of a model terminal exceeds 1 million units, it is necessary to apply for another TAC. In accordance with the relevant requirements of TS.06 (DG06)IMEI Allocation and Approval Guidelinesv8.0 (IMEI Allocation and Approval Guidance Document) issued by the GSMA, with effect from 22 June 2015, A TAC can correspond to only one product model.
3. The meaning of verification code
Check Digit can be calculated by Luhn formula (ISO/IEC 7812), the specific calculation method is referred to 3GPP TS 23.003 Appendix B requirements. The verification code is used by the enterprise to verify all other digits of the IMEI and is not used by the carrier.
