Open a terminal with the modem plugged in and use the command "lsusb". Look for a listing of the modem as a device in the form, ID xxxx:xxxx. Go to the Internet, search with the ID number to find out how this device is supported in linux, and how to get the dial-up to your Internet service provider with linux .
You probably need to use USB_ModeSwitch, and probably need to compile it yourself for it to work with your kernel. There is help, information, and a forum at the Draisberghof site.