How to check balance and validity of any BSNL mobile number online

BSNL is India's most popular cellular service provider. It offers mobile calling services, high speed 2G/3G data plans, Landline and broadband plans etc. Most of the people who are in government services use BSNL. Well, some of your friends might be using BSNL. Do you want to check their account balance and validity without touching their phone? I'm gonna share a trick to check balance and