How are devices like smattphones given unique IDs (IMEI numbers, MAC addresses) during the manufacturing process?
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I work with cellular devices that requires unique IDs such as what you described. Smartphones would generally all work in a similar fashion but the details would be considered trade secret, of course. It starts with factory serial number which is flashed to the device when it’s still in the assembly line. The format is unique to each manufacturer but they generally follow a system of model code name, dates, batch, and sequence. Then the IMEI, MAC and anything else unique (default wifi SSID, SIM lock password) are written much later, usually in the last step before boxing. The IMEI has a special format. The first 8 digit is called TAC and has to be registered by the manufacturer. They are normally unique to each model, or a subgroup of a model. The next 6 is normally programmed in sequence. Then the last digit is checksum. Once you use up a million IMEI in your TAC range, you must register another TAC code. This ensures the IMEI for each device is unique in the world. In comparison, The first half of the MAC address is also registered by the manufacturer, but it’s only to the manufacturer not model. And the second half, 6 digit hexadecimal numbers are cycled through the history of the manufacturer so there’s an almost impossible chance your MAC could collide. Then other unique code like SIM unlock codes are generated for each device but they’re not required to be unique.
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