First you need to move the modem to "modem only" for this you will need a terminal, you can use Hyper Terminal on windows.
Google search for AT commands for your modem to make it modem only mode and how to do that.

All right .... transferred the modem to the modem-only mode ....

Then note the vid and pid of your modem. one way to do this is to connect the modem to computer,
 then go to device manager, expand modems, right click your modem >properties>details.


2. Next we need ES File Explorer