The LW272 and LW273 3G data-cards of BSNL do not support any other SIM.
On inserting any other Sim it says "Invalid Sim. Data-card will close"
Here is an method by which you can use any other SIM on BSNL 3G Data.
Just Follow the following steps*.
1. Go to Registry edit (Run-> regedit )
2. Search for Linktop3G.
3. In options of Linktop3G. you will see an engineer key. Open it and change its key to 0 from 1 ( by doing this, your data-card will not close on inserting some other Sim)
4.Here I m using Airtel SIM for demonstration. Now make new settings in connection option. for airtel use apn as airtelgprs.com
5. Now search for the Airtel network. As soon as u get the network.
6. Open the network sharing from control panel. Make a new Dial up connection
7. Use *99# as dialing number . Leave rest options as blank.
8. By following all these steps. You will be connected to internet.
* I m not responsible for any kind of harm happens to your computer or data-card by this steps. Do at it your own risk.