An IMEI (International Mobile Equipment Identifier) is a 15-digit number associated with a mobile phone. Every individual phone has a unique IMEI. The IMEI is a little like an electronic serial number that uniquely identifies an individual mobile to the network. Some mobile service providers have the capability to maintain a ‘blacklist’ of IMEI’s associated with phones that have been reported stolen. Phones with IMEI values included in the blacklist are automatically prevented from accessing the service providers network.