The Type Allocation Code (TAC) is a portion of the 15-digit IMEI code used to uniquely identify wireless devices. The Type Allocation Code is an 8-digit number that identifies a particular model (and often revision) of wireless telephone for use on a GSM, UMTS, or other IMEI-supporting wireless network. Prior to April 1, 2004, the global standard for the IMEI included the 6-digit Type Approval Code (also known as TAC), which indicated that the particular device was approved by a national GSM approval body; and the Final Assembly Code (FAC), which could uniquely indicate the manufacturing company that had actually built and assembled the device (which is not always the same as the brand name stamped on the device). Effective on that date, many GSM member nations and entities (mainly Europe) moved away from requiring that devices be approved by national bodies, and towards a system where device manufacturers self-regulate the device market. As a result, a manufacturer now simply requests TAC codes for new phone models from the international GSM standards body, instead of submitting a device for approval to a national review body. With both the old and new TAC, the code can be used to uniquely identify the model of phone being used (although some models may have more than one code, depending on revision, manufacturing location, and other factors). Also in both TACs, the first two digits indicate the country of origin of the device. (In a Type Approval Code, this indicates the country of the national body that approved the device.) These codes are generally based on the ITU-T E.164 country codes that are used for international phone dialing, with some variations (for example, 50 indicates Taiwan; 35 indicates Finland).
