An IMEI number is a unique identifier for cellular devices. It stands for International Mobile Equipment Identity number and you can usually find it printed on your hardware or within your device’s settings. They are usually 15 digits long and completely unique to your device.

Breaking down IMEI numbers

IMEI numbers are made up of a 15-digit code. It can be split into the following sections…

• Reporting Body Identifier (RBI)
  A 2-digit code that outlines the GSMA-approved group that allocated the TAC.
• Type Allocation Code (TAC)
  6-digit code that outlines the model and origin of your device.
• A serial number (SN)
  6-digit number that is unique to your device.
• Check digit (L)
  This is generated by the Luhn algorithm.

All IMEI numbers follow the same format:

RBI+TAC+SN+L

For example:

35 (RBI) + 012345 (TAC) + 123456 (SN) + 0 (L)

In this example, your device’s IMEI number would be 350123451234560.

What is the purpose of an IMEI number?

IMEI numbers are used by mobile network operators (MNOs) to identify and verify a device when it tries to connect to their network. If the IMEI of the device matches an authorised identifier on the global IMEI database, then it will be permitted to traverse data over the network. If it doesn’t match an authorised identifier, then the device will not be granted permission to utilise the network. This is a very common occurrence when it comes to mobile phones as many handsets are locked to specific networks upon purchase.

They can also be used to identify devices when they have been lost or stolen. Reporting the IMEI of a missing device to the police can help make sure it is returned to the rightful owner. For this reason, it’s important you make a note of your IMEI numbers and keep them safe. You should never share these device identifier codes with third parties for security reasons.

If your cellular devices are being misused or not adhering to fair usage policies set out by the networks, MNOs have the ability to blacklist IMEI numbers via the global IMEI database. Since all networks can access the database, a blacklisted identifier would prevent your device from being able to operate on any network. It can be a very difficult process to get an IMEI number removed from the blacklist once it has been added.

Mobile Telephones (Re-Programming) Act

Many countries and law enforcement agencies use IMEI numbers to combat cybercrime. In the United Kingdom, the Mobile Telephones (Re-Programming) Act makes it illegal for anyone to own equipment that can change the IMEI number of devices.

Did you know

• You can find out the IMEI number of almost any mobile handset by using the dial pad and typing *#06#.
• The IMEI number of a device is assigned by the manufacturer. Whilst it is possible to change an IMEI number, it’s illegal to do so in many countries as it prevents devices from being identified. We strongly advise against making changes to IMEI numbers.