MOBILE PHONE IMEI CODES


The IMEI (International Mobile Equipment Identity) is a unique 15-digit code used to identify an individual GSM mobile telephone to a GSM network. The IMEI can be found on most phones by dialling the code *#06#. The IMEI is also normally printed on the text sticker underneath the space where a mobile phone battery is fitted.

The IMEI provides a unique indentifier for each mobile phone on a GSM network, which means that if a mobile phone is stolen, the network carrier can block the use of the mobile phone itself, as well as the phone number. The key to this is the GSM network carriers operating an Equipment ID Register (EIR) for IMEI codes, to prevent use of the mobile phone on other networks. Certainly most European network carriers have an EIR.

Using this system means that when a mobile phone is switched on, the unique IMEI is transmitted across the mobile phone network and is checked against a database of blacklisted or greylisted phones in the network carrier's EIR. The EIR then determines whether the mobile phone is allowed to log onto the network to make and receive phone calls.

If the EIR and IMEI numbers match, the network carriers have several options; If the mobile phone has been reported stolen, the network carriers can decide to greylist or blacklist a phone:

An IMEI code is divided into four sections, with each section separated by a space as shown by this example:

49 8762 35 123456 0
cc tttt ff ssssss p
TAC FAC SNR SP

IMEI Code Details.

The table below provides more detail on the 4 individual items that combine to make up the IMEI number.

Section Details Example
TAC Type Approval Code - The first 6 digits of the IMEI represent the Type Approval Code (TAC) of the mobile phone. The first two digits of the TAC identify the country in which Type Approval was granted for the mobile phone. The TAC also identifies the Approval Number. 498762
FAC Final Assembly Code - The Final Assembly Code (FAC) identifies the facility where the phone was assembled. e.g. Motorola, Nokia, etc. 35
SNR Serial Number - The Serial Number provides a unique number for the mobile phone handset 123456
SP Spare - This is a spare digit. Usually, this digit is 0 0

FAC (Final Assembly Code) Details.

The table below provides more detail on the FAC (Final Assembly Code) numbers for manufacturers, used in the IMEI number.

Final Assembly CodeManufacturer
01AEG
02AEG
07Motorola
10Nokia
20Nokia
30Ericsson
40Motorola
40Siemens
41Siemens
44Siemens
50Bosch
51Sony
51Siemens
51Ericsson
60Alcatel
70Sagem
75Dancall
80Philips
85Panasonic

Is posting details of the IMEI code sequence irresponsible?

No, not at all. If anything it adds to security, since if more people are educated as to the details of the IMEI number, and it results in more people noting down their IMEI number, so that if they report a mobile phone stolen, they report the IMEI number at the same time, then the people who will lose out are those who wish to use a phone for criminal gain. In combination with using a phone lock code and SIM card security code, this should make mobile phone theft a lot more taxing on the thief.

IMEI Security for mobile phones

Whilst noting down an IMEI number for a mobile phone, and keeping that number stored safely, is a good idea, it should not assumed that this will prevent any use of the mobile phone. The IMEI number is stored in rewriteable flash memory on a mobile phone, which means the IMEI number can be overwritten with appropriate reprogramming equipment.

If this page was useful, you may also want to read:

IMSI Number - International Mobile Subscriber Identity Number
SIM Cards
Smartcards

Acronym Glossary.

SIM - Subscriber Identity Module
IMEI - International Mobile Equipment Identity
FAC - Final Assembly Code
TAC - Type Approval Code
SNR - Serial Number
EIR - Equipment ID Register



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