What is IMEI? The International Mobile Station Equipment Identity or IMEI is a number, usually unique,to identify 3GPP (i.e., GSM, UMTS and LTE) 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 *#06# on the dial-pad, or alongside other system informatio..