An International Mobile Equipment Identity (IMEI) is used to uniquely identify GSM and iDEN devices on a network.
Devices that operate on GSM networks use an International Mobile Equipment Identity (IMEI) to identify themselves to the network. This number is associated with the device itself, and not the SIM card that is inserted (which has an IMSI instead). CDMA devices will use an esn to uniquely identify themselves rather than an an IMEI.
