International Mobile Equipment Identity

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The International Mobile Station Equipment Identity (IMEI) is a unique 15-digit serial number, which the light of each GSM - or UMTS - the terminal can be uniquely identified worldwide. Dual SIM phones have two IMEI numbers.

The IMEI is known to the general public for its ability to block a stolen cell phone from cell phone network operators. After blocking, the mobile phone cannot be used with another SIM card . The IMEIs concerned are kept in lists for this purpose. The IMEI can only be used to a limited extent for theft protection, as the IMEI of a cell phone can be reprogrammed with the appropriate software. For more details on these lists and their inadequate suitability for theft protection, see the Equipment Identity Register (EIR).

The IMEI should be kept so that the device can be reported to the police as stolen in the event of theft. The IMEI is also often required to remove a SIM lock .

Displayed IMEI of a Sony Ericsson mobile phone


The IMEI of a mobile phone can be queried by entering * # 06 # in the input field for the telephone number. This key code is uniformly prescribed in the GSM standard.

On many cell phones, the IMEI can also be found on the nameplate or packaging. For phones where the battery can be removed, this information is usually located under the battery.

On iPhones and iPads , you can also find your IMEI under Settings> General> Info.

For older Ericsson - as well as most Sony Ericsson -models the IMEI can also be accessed with the following key combination: ***.


IMEIs of end devices that have been approved since April 1, 2004 consist of three parts:

  • The first eight digits form the TAC (Type Allocation Code). The first two digits of the TAC consist of a Reporting Body Identifier (RBI) and indicate the approving accreditation body. The remaining six digits contain the pass code. The TAC is unique for different terminal hardware and can be used to identify a terminal type.
  • The next six digits form the actual serial number of the end device (SNR).
  • The last digit is the check digit CD (Check Digit). In GSM phase 1 devices it is '0', from phase 2 it is occupied. The check digit is only saved in the device; when transmitted in the network, a '0' is always transmitted. The algorithm for the calculation is documented in 3GPP TS 23.003, Appendix B.

Until 2002 the TAC was only six digits long and provided information about the manufacturer. This was followed by a two-digit Final Assembly Code (FAC) with another manufacturer-specific identifier. During the transition period from January 2003 to the end of March 2004, two zeros were used instead. Both positions have been part of the TAC since April 2004.

Some end devices also have a two-digit identifier for the software version in the device, the software version number (SVN). This is not part of the IMEI, but is often output when queried with * # 06 #.

Uniqueness of the IMEI in practice

While the standard provides that an IMEI is unique and protected from manipulation by the user, in practice this is not the case. Many devices that have been on the market since 2002 can manipulate the IMEI. In 2002 the BBC published a report that said about 10% of IMEIs were ambiguous. The GSMA itself places the responsibility for compliance with the standards and thus the uniqueness of the IMEI as well as protection against manipulation in the hands of the device manufacturer, but admits that the standards are poorly applied, especially outside the European Union. The fact that the majority of device manufacturers are based outside the EU shows that the security and uniqueness of IMEIs cannot be guaranteed.

See also

  • IMSI for the unique identification of network subscribers in GSM and UMTS cellular networks
  • IMSI catcher for eavesdropping on cell phone customers
  • SIM card in the mobile phone to identify the user in the mobile network
  • Mobile phone tracking
  • Stealth Ping - also Silent SMS or Silent SMS to locate cell phones or to create movement profiles
  • Cell-ID is a method of mobile positioning in the GSM cellular network

Web links

Commons : IMEI  - collection of images, videos and audio files

Individual evidence

  1. 3GPP TS 22.016: International Mobile Equipment Identities (IMEI) ( English , ZIP / DOC; 36 kB) October 1, 2009. Accessed December 3, 2009.
  2. Nokia FAQ - Do I have two IMEI numbers on my Nokia mobile phone? Retrieved January 5, 2014.
  3. a b 3GPP TS 23.003: Numbering, addressing and identification ( English , ZIP / DOC; 283 kB) September 29, 2009. Accessed December 3, 2009.
  4. Phone firms defend security record ( English ) BBC. January 8, 2002. Retrieved May 17, 2016.
  5. GSME proposals regarding mobile theft and IMEI security ( English , PDF) GSM Europe. P. 4. Retrieved May 17, 2016.