The spelling mistake in the title was intentional.
International Mobile Equipment Identifier
A 15 digit number unique to each mobile phone/device on GSM networks and numbers and letters on CDMA networks and is unique to the SIM card.
The number is in 4 groups of digits: xxxxxx--xx-xxxxxx-x - although it will be displayed as just a long sequence of digits.
- The first group of numbers is the TAC (Type Approval Code), of which the first 2 digits are the country code. "This code identifies the country in which type approval was sought for the phone, and the approval number. The first two digits of the TAC represent the country of approval." 3
- The second group of digits, the FAC (Final Assembly Code), represents the manufacturer of the device.
- The third group of digits is a serial number of the device.
- The last digit is usually 0 but on later devices, a checksum digit.
There has also been talk (4
) of there being an additional 2 digits added to the end of the code (the SVN - Software Version Number).
There is some debate as to whether the first 2 digits is the approving country or not. It is - I checked with some friends of mine who write software for mobiles for a living!
The IMEI of a phone is used along with the unique number of the devices SIM card to produce an encryption key to be used in the communications.
Networks can 'see' the IMEI and use it to track devices, allow services (white listing) or even ban devices from the network (black listing).
To find out your IMEI number, just type *#06# into your phone and the number should just appear.
PS. lj points out http://www.nokiaport.de/imei/imei.htm which has a comprehensive list of Nokia TACs.