IMEI is a very useful identification number that is unique to every mobile or satellite phone.
It is a 15-17 digit code and usually found on the inside of battery compartment in every phone and used to track lost phones.
Infact you can check your phone's IMEI .Here are three common ways to check IMEI of your phone :
1. Type *#06# on the phone's dial pad.
2.Look under the battery.
3.Look in settings. Settings, then About phone, and then Status then IMEI information.