The International Mobile Equipment Identity or IMEI is a number unique to every GSM and UMTS mobile phone as well as some satellite phones. It is usually found printed on the phone underneath the battery.
The IMEI number is used by the GSM network to identify valid devices and therefore can be used to stop a stolen phone from accessing the network. For example, if a mobile phone is stolen, the owner can call his or her network provider and instruct them to "ban" the phone using its IMEI number. This renders the phone useless, regardless of whether the phone's SIM is changed.
The International Mobile Equipment Identity - a unique 15-digit code used to identify an individual GSM mobile telephone to a mobile network. It can be displayed on most phones by dialling *#06#. It is also usually printed on the compliance plate under the battery.
Prior to April 1st 2004 the numerical format of the code was:
111111-22-333333-4
| TAC | FAC | SNR | CD | |||||||||||
| D14 | D13 | D12 | D11 | D10 | D09 | D08 | D07 | D06 | D05 | D04 | D03 | D02 | D01 | |
- TAC: Type Approval Code
- FAC: Final Assembly Code
- SNR: Serial Number
- CD: Check Digit
The first six digits are the TAC (Type Approval Code), which identifies the country where type approval was sought for the phone, as well as the approval number. NOTE: since the 1st April 2004 the TAC will be the abbreviation for Type Allocation Code.
The FAC (Final Assembly Code) identifies the company that produced the mobile phone (eg: SonyEricsson or Nokia). NOTE: From 1st January 2003 a new code allocation procedure has been in place. The changes relate to the format - the Final Assembly Code (FAC) is obsolete and is set to 00 for the period from 1st January 2003 until 1st April 2004. The FAC is now obsolete, and the TAC is now eight instead of six digits, as follows: 11111111-222222-3
| TAC | SNR | CD | ||||||||||||
| D14 | D13 | D12 | D11 | D10 | D09 | D08 | D07 | D06 | D05 | D04 | D03 | D02 | D01 | |
The 6 digit SNR (Serial Number) has been uniquely assigned to the specific type of handset. The CD (Check Digit) is used to check the code for its validity for Phase 2 and Phase 2+ handsets. Phase 1 GSM handsets, however, always have zero ("0") as check digit.
IMEISV (International Mobile Equipment Identity and Software Version number) is also sometimes used. It offers the possibility of adding the handset's original software version number. It adds a two digit SVN (Software Version Number) at the end of the code, so the numerical format is:
111111-22-333333-4-55, which changed to 11111111-222222-3-44 on 1st April 2004.
Post Source:
http://en.wikipedia.org/wiki/International_Mobile_Equipment_Identity
http://www.orate.co.uk/Mobiles/imei.html
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