29 December 2009. GSM A5 Files Published on Cryptome

11 December 1999
Source: http://www.gsmworld.com/news/news_releases_35.html

GSM Association News, December 10, 1999

SMG Plenary agrees to secure integrity of IMEI

The IMEI (International Mobile Equipment Identity) is a unique number assigned by manufacturers to each GSM mobile phone produced. It was initially produced for type approval reasons so that out of specification mobile phones may be removed from a network.

It is common knowledge that, almost without exception, GSM mobile phones can have their identity easily changed. This is due to the fact that the GSM specification does not explicitly exclude re-programming of the IMEI by authorised individuals.

Responding to these issues raised by operators the SMG Chairman at the recent SMG Plenary - which is responsible for the definition of the GSM specification - decided to further secure the integrity of IMEI although this will not stop internal modifications to the mobile phone, such as memory, being used to modify the IMEI. This benefits the regulator, the operator, the manufacturer and ultimately the consumer.

The regulator benefits by being able to ensure that type approved handsets are used on networks and that mobile phones can be identified for the purposes of lawful interception and criminal prosecution. The operator benefits in many ways - including:

• allowing mobile phones to be identified to allow added value services and enhanced functions to be run.
  
• allowing an operator to determine which mobile phones may be responsible for technical issues on a network, for example dropped calls or handover problems.
  
• preventing stolen mobile phones from being re-used on networks to prevent crime, which may have great consequential problems (for example car theft and insurance) and social impact.

Manufacturers benefit by being able to identify grey market handsets and by reducing theft levels in the distribution channel.

In the future consumers can be assured that the handsets they buy have not been stolen. In addition, a secure IMEI can allow a customer to prove purchase for warranty purposes. The changes will also be carried forward into 3GPP so that 3rd generation mobile phones will not have easily changed IMEIs.

10 December 1999

For more information, please contact:

Mary King
GSM Association
Tel: +353 1 269 5922
Fax: +353 1 269 5958
Email: info@gsmworld.com

Source: http://www.brookson.com/gsm/gsm.htm

The GSM Association algorithms are now only available from Dublin:

• A5/1

• A5/2

• COMP 128-2 (The new variant)

You should request an information pack get the algorithms from:

james.moran@gsm.org