DataFox is a bandwidth usage monitor for BSNL DataOne and MTNL TriBand. It is a cross platform extension written for Firefox that shows data usage statistics on the Firefox status bar. It's an absolutely great add-on for BSNL BB users (Who use Firefox 
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If you're using Firefox, click here to install the extension directly
Visit Homepage : Thegoan
You can right click the status bar icon to bring up the following options:  Update | Forces the usage data to update, has the same effect as clicking the  icon. |
 Logout | Allows you to re-enter your account details the next time you update. |
 Show Records | Display your usage records in the browser, you may choose to see records of either the active month, or the selector for all months. |
 Month (BSNL Only) | Choose the month for which usage data is fetched. DataFox will allow you to choose one of six months as this is the extent of the records available online. In case data for a month does not exists (say, if you have only been using DataOne for three months) then DataFox will display an error message when trying to fetch the usage info. |
 Preferences | Brings up the DataFox preference dialog (see below). Can also be invoked from the Tools menu. |
| Login Dialog options: Override default domain (BSNL Only) | By default, DataFox first queries sancharnet.in for the appropriate address at which your usage can be checked. I assume it sends you to a server in your region for the quickest response. In case you wish to specify your own address or in case the redirect is not working for some reason, check the box and choose an address from the list or enter your own. |