International Mobile Equipment Identity

The International Mobile Equipment Identity (IMEI)^[1] is a numeric identifier, usually unique,^[2][3] for 3GPP and iDEN mobile phones, as well as some satellite phones. It is usually found printed inside the battery compartment of the phone but can also be displayed on-screen on most phones by entering the MMI Supplementary Service code *#06# on the dialpad, or alongside other system information in the settings menu on smartphone operating systems.

GSM networks use the IMEI number to identify valid devices, and can stop a stolen phone from accessing the network. For example, if a mobile phone is stolen, the owner can have their network provider use the IMEI number to blacklist the phone. This renders the phone useless on that network and sometimes other networks, even if the thief changes the phone's SIM card.

Devices without a SIM card slot or eSIM capability usually do not have an IMEI code, except for certain early Sprint LTE devices such as the Samsung Galaxy Nexus and S III which emulated a SIM-free CDMA activation experience and lacked roaming capabilities in 3GPP-only countries.^[4] However, the IMEI only identifies the device and has no particular relationship to the subscriber. The phone identifies the subscriber by transmitting the International mobile subscriber identity (IMSI) number, which is stored on a SIM card that can, in theory, be transferred to any handset. However, the network's ability to know a subscriber's current, individual device enables many network and security features.^{[citation needed]}

Dual SIM enabled phones will normally have two IMEI numbers, except for devices such as the Pixel 3 (which has an eSIM and one physical SIM) which only allow one SIM card to be active at once.