MTNL is is one of the widely used ISP in Delhi and Mumbai here in India, they provide quite nice services at a very cheap rates as compare to other ISPs.
But the problem is that the staff of MTNL is very poor and if you call them then you have to wait a long to get your answer. If you are on a limited connection of MTNL and if you need to know how much data you had used and how much is left in your account then you can call them but many time you wont get your answer.
So here is a simple way to view how much data you had used and how much is left in your account for the month.
First you need to login to MTNL Web-Self Care service HERE,
Use your telephone number as your Username and Consumer Number as your password, you will find your Consumer Number on your telephone bill.
Once you login click on Account Summary from left sidebar and then you will get all info of your account,
MB used referred as MB you had used on downloading, email viewing, Surfing, Chatting , on line games, Videos and Songs etc. Any data received from Internet is treated as MB downloaded.
ADSL MB Indicate Free MB Left in your account. In above screenshot you wont find this option as I am on unlimited plan.
P.S. We had tested and found this will not work if you are working on Opera.