Mobile Phone Technology

Each mobile network needs to keep lists of equipment that can and cannot connect to their network. This is to ensure the integrity of the network. The Equipment Identity Register (EIR) is part of the core of the network. It maintains lists of equipment that has tried to connect to a mobile phone network. Each device trying to connect to the network has a unique IMEI, which is a unique number allocated by manufacturer. This is used to Authenticate (or not) a device when it tries to connect. The register maintains 3 lists :

• White List - the first time a piece of (valid) equipment tries to connect to a mobile network it is put onto the White List. All future connection will check that the device is on this white list.
• Black List - this is the list of barred equipment; stolen or devices that when they are connected have had a negative effect on the network - they do not confirm to the network standards.
• Grey List - the list of equipment that is classed as non-conforming. They are not bared but do not conform in some way.

In 4G / 5G networks the EIR is run as a service-based architecture through a third party that allows the sharing of data between the (UK) operators. When a device attempts to connect to a network the mobile network will use the API to this service to allow (or not) the device to connect. Phones stolen and sold on within the UK will have the IMEI put onto the "Black-List" and not be permitted to connect to any Uk mobile network. Information is shared between "friendly" countries to stop the traffgic in stolen phones across borders..