IMEI International Mobile Equipment Identity number is unique to each mobile handset regardless of the technology it handles like GSM, CDMA, UMTS MS, or even Multi-mode MS. This IMEI number is set by the manufacturer in the factory itself. Hence it cannot be changed or erased. All IMEI numbers are allocated and comply with the standards of mobile communication which is 3GPP TS 22.016 and its equivalents. IMEI numbers are used in IMEI number tracking to identify where the cell phone is currently in use for tracking the lost mobile phones and in CBI investigations. IMEI number varies across manufacturers like Samsung IMEI number, Nokia IMEI number etc.

IMEI Number is necessary for each and every mobile handset. Indian telecom regulator TRAI announced that all mobile phones without IMEI number will be banned. Most of these non-IMEI phones are china mobiles. Now there is a facility to register the IMEI number in the non-IMEI mobile phone and a deadline to register in this. People are seen in the queue to register the IMEI numbers in the china mobiles. Special IMEI number registration centers are there to do this across the nation.