IMEI
All GSM and UTMS mobile phones have an IMEI, which stands for International Mobile Equipment Identity. The IMEI is a 15-17 digit number which facilitates easy identification for mobiles that are being used on the aforementioned networks, and can be used to stop stolen phones from accessing the network, rendering them less useful.
Mobile phone owners who have lost their phones – especially when they suspect that the mobile device has been stolen – can contact their service provider and request that the mobile phone be shut out from the network. The service provider would then use the IMEI to exclude the particular number from its network, should it be inclined to do so. Even changing the SIM card will not be enough to make it work again on that network.
Along with the IMEI number, mobile phones typically include information on the origin, model and the serial number. Subscribers may retrieve the IMEI for their handsets by dialing *#06# into their mobile phones. Retrieving other details may be dependent on the handset. For instance, if your phone is Sony Ericsson, you can retrieve them by entering these keys: Right * Left Left * Left *. Nokia users on the other hand may retrieve them by pressing *#92702689#.
Structure of an IMEI Number
The number of digits for an IMEI number may be anywhere between 15 and 17.
If the number of digits is 15, the IMEI digits are 14 and the 15th digit is called the check digit. As of the year 2004, the format of a typical IMEI number would be AA-BBBBBB-CCCCCC-D though this is not how the number would always be displayed.
The first two digits are for the Reporting Body Identifier which indicates the GSMA group that allocated the Type Allocation Code (or TAC).
The second set of six numbers (BBBBBB) represents the remainder of the TAC. The CCCCCC is the serial sequence of the particular model.
The last one, called the Luhn Check digit, is a number generated to validate the ID number based on a checksum formula.
Use of IMEI
Governments all over the world have come to acknowledge the usefulness of IMEI as a way to curb rising cases of mobile phone thefts. A user may call the Central Equipment Identity Register and report that a certain mobile phone has been stolen and the CEIR may blacklist the phone. CEIR maintains a database of blacklisted phones that have been denied access to the operators’ networks.
Limitations of the IMEI
A significant drawback of IMEI is that it is possible to change the IMEI using special equipment. In addition, not all network operators blacklist mobile phones that are registered with CEIR. There are statistics that suggest that almost a tenth of the current IMEIs on use today are not the original and have been programmed. This has spurred some governments to act by passing even tougher legislation. In UK for instance, it is an offence under the Mobile Telephones (Re-programming) Act to change the IMEI of a handset, or even possess equipment that can be used to change it.
For more information on IMEI read What is an IMEI?