What is an IMEI?

IMEI is an acronym that stands for International Mobile Equipment Identity. Each GSM and UMTS mobile phone has a unique IMEI number. IMEI number facilitates an important function; it easily identifies a mobile phone being used on a GSM (Global System for Mobile Communications) network. The IMEI is a useful tool to stop a phone that is stolen from accessing a network and being used. Mobile phone owners that have their phones stolen can contact their mobile network provider and ask them to ban or shut off a phone using its IMEI number. With an IMEI number, the phone can be banned from the network quickly and easily. It is important to note that swapping a SIM card will not stop a phone from being banned.

An IMEI device is only used to identify the device and does not usually relate to a specific individual or organization. Other numbers such as ESN (Electronic Serial Numbers) and MEID (Mobile Equipment Identifiers) can link an individual to a phone. Usually, an IMSI number stored on a SIM card can identify the subscriber on a network.

There are a few ways in which you can locate your mobile phone's IMEI number, it can usually be found on the handset, beneath the battery, sometimes printed on a small white label. Another way to easily locate your IMEI phone is to dial the following sequence of numbers into the handset: *#06#. If you have a Sony Ericsson mobile phone, you can retrieve the IMEI by pressing the following key sequence: right,*, left, left,*, left, *, left.

The Structure of an IMEI Number

IMEI numbers either come in a 15 digit or 17 digit sequences of numbers. These numbers can identify a handset. Currently the format of the IMEI is AA-BBBBBB-CCCCCC-D.

These two digits are for the Reporting Body Identifier, indicating the GSMA approved group that allocated the TAC (Type Allocation Code).
BBBBBB- The Remainder of the TAC
CCCCCC- Serial Sequence of the Model
D- Luhn Check Digit of the entire model or 0 (This is an algorithm that validates the ID number)

Central Equipment Identity Register (CEIR)

If a mobile handset is lost or stolen, as the owner or operator of the device, you can contact the CEIR which will blacklist the device in all currently operating switches. This makes the lost or stolen handset unusable. The action of blacklisting stolen mobile handsets is seen as a deterrent to crime, however, it is possible to change an IMEI with special tools and there are certain mobile networks that do not automatically blacklist handsets registered with the CEIR. Current statistics state that about 10% of current IMEI's in use today are not unique or have been reprogrammed (hacked).