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# International Mobile Equipment Identity

The IMEI is an assigned number (not always unique) which identifies most mobile phones and on GSM networks (ie. AT&T, Vodafone, TMobile, etc) it can be used to identify valid devices; preventing a stolen cellular phone from accessing the phones host network in the country of origin. Most frequently the manufacturer places a printed label inside the battery compartment (see above) but it can also be viewed on screen by entering *#06# on the keypad of most phones.

Note: A more comprehensive explanation is available on WikiPedia.

### The fourteen digit IMEI number (IMEISV has 16) is generated according to the Luhn Algorithm. This dictates that the check number will comprise

The Check Digit is a function of all other digits in the IMEI.:

1. Starting from the right, double a digit every two digits (e.g., 7 ? 14).
2. Sum the digits (e.g., 14 ? 1 + 4).
3. Check if the sum is divisible by 10.

Conversely, one can calculate the IMEI by choosing the check digit that would give a sum divisible by 10. For the example IMEI 49015420323751?,

 IMEI 4 9 0 1 5 4 2 0 3 2 3 7 5 1 ? Double every other 4 18 0 2 5 8 2 0 3 4 3 14 5 2 ? Sum digits 4 + (1 + 8) + 0 + 2 + 5 + 8 + 2 + 0 + 3 + 4 + 3 + (1 + 4) + 5 + 2 + ? = 52 + ?