IMEI (international mobile equipment identifier)

A unique 15-digit number that serves as the serial number of the GSM handset. (Cingular)

The International Mobile Equipment Identifier (IMEI) is a 15-digit number (composed of four parts) that uniquely identifies an individual wireless phone or communicator. The IMEI appears on the label located on the back of the phone. The IMEI is automatically transmitted by the phone when the network asks for it. A network operator might request the IMEI to determine if a device is in disrepair, stolen, or to gather statistics on fraud or faults. (Nokia)

The IMEI is an individual number, unique to a particular phone, which can be used to identify it. The first 6 digits of the IMEI identify the manufacturer and exact model (e.g. Motorola Timeport P7389), the last digits identify the particular phone in that range. (Motorola)

The International Mobile Equipment Identity (IMEI) is a number unique to every GSM and UMTS mobile phone. It is usually found printed on or underneath the phone's battery and can also be found by dialling the sequence *#06# into the phone.

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 "bar" the phone using its IMEI number. This renders the phone useless, regardless of whether the phone's SIM is changed.

Unlike the ESN of CDMA and other wireless networks, the IMEI is only used to identify the device, and has no permanent or semi-permanent relation to the subscriber. Instead, the subscriber is identified by transmission of an IMSI number, which is stored on a SIM card which can (in theory) be transferred to any handset. However, many network and security features are enabled by knowing the current device being used by a subscriber.

Retrieving IMEI information from a GSM device

The IMEI number of a GSM device can be retrieved by sending the command AT+CGSN. For more information refer the 3GPP TS 27.007, Section 5.4 /2/ standards document. On many devices the IMEI number can be retrieved by entering *#06#.

Retrieving IMEI Information from a Sony Ericsson handset can be done by entering these keys:

Right * Left Left * Left * Left

IMEI and Law

Many countries have acknowledged the use of the IMEI in reducing the effect of mobile phone theft, which has increased exponentially over the last few years. For example, in the United Kingdom under the Mobile Telephones (Re-programming) Act, changing the IMEI of a phone, or possessing equipment that can change it, is considered an offence under some circumstances.

There is a misunderstanding amongst some regulators that the existence of a formally allocated IMEI number range to a GSM terminal implies that the terminal is approved or complies with regulatory requirements. This is not the case. The linkage between regulatory approval and IMEI allocation was removed in April 2000 with the introduction of the European R&TTE Directive. Since that date, IMEIs have been allocated by BABT (acting on behalf of the GSM Association) to legitimate GSM terminal manufacturers without the need to provide evidence of approval.

Blacklist of stolen devices

When mobile equipment is stolen or lost, the operator or owner will typically contact the Central Equipment Identity Register (CEIR) which blacklists the device in all operator switches so that it will in effect become unusable, making theft of mobile equipment a useless business.

The IMEI number is not supposed to be easy to change, making the CEIR blacklisting effective. However this is not always the case: IMEI may be easy to change with special tools and operators may even flatly ignore the CEIR blacklist.

Difficulties

* "New IMEIs can be programmed into stolen handsets and 10% of IMEIs are not unique." According to a BT-Cellnet spokesman quoted by the BBC.[citation needed]
* Facilities do not exist to de-bar numbers listed in error.

(Wikipedia)