Let’s get to know basics first.
1. IMEI stands for International Mobile Equipment Identification.
2. Every cellphone/mobile are assigned 15 digit unique IMEI numbers (except the chinese ones).
3. To know your mobile IMEI number type *#06# on your mobile (note down this IMEI number) alternatively you can also find your mobile IMEI number on your mobile box(cover).

How to block lost or stolen mobiles using IMEI number
Functionaning – When your mobile phone is switched on the SIM card tries a handshake with any available network, once recognising the supported network it tries to build a network connection between your mobile handset and the nearest tower. While this handshake is happening your SIM transfer some crucial information to the network operator in from of your IMEI number, mobile model, version etc. The catch here is your mobile operator (Airtel, Idea, Vodafone) keeps the record of your mobile handset number every time you switch on your mobile.

Process – Now if your mobile is lost or stolen you can contact your network provider to block mobile having this IMEI number. However there is a possibility to get a Police FIR copy. This makes your network provider to put your phone’s IMEI no in a shared database called as an Equipment Identity Register (EIR) which reduces the threats of theft of handsets by enabling individual operators to prevent the use of stolen handsets in their own network. Mobile network providers use a shared hosting service for blocking IMEI numbers,means if you have asked network Airtel to block your mobile handset, it automatically gets blocked by network Vodafone, Idea.

Now to make the stolen phone inaccessible in other networks (service providers) also, your IMEI no is transferred to Central Equipment Identity Register (CEIR) which is a database of the IMEI numbers of blacklisted handsets. Once the device number is listed on CEIR, it wouldn’t work with any of the network provider.

Want to know more about your IMEI no. go to numberingplans and know more about your handset model, manufacturing date and some internal informations for free.