How to check BSNL 2G/ 3G GPRS usage on datacard modem code?

Hi
I just purchased new SIM of bsnl and have made recharged with gprs 1.25 2G gprs pack and now I need to know how I can check usage in it for remaining data myself ?
I want this because in mobile after usage it shows remaining data but if I use it on data card then how can I get to know it because when using data card or the usb modem, it never shows usage automatically after disconnecting so I think I need to know the code. I search net and some said you need *124*4# but that is not working and saying unknown application.

It is very easy for prepaid connection, I don't know about postpaid though, all you need is to dial
*123*6#, I have verified it. And it works for 3G data too.