Go back to
www.google.com and see if the modem will work in Linux with a work around. There are adapters that have USB on one end and RS-232 serial connection on the other end. If YOU plug the RS-232 end into YOUR RS-232 serial port on YOUR computer, YOU might get the system to recognize the USB modem without using the the USB ports. Linux can be configured to use PPPoE, PPPoA, or Ethernet. But straight through the USB port is not spoken of often. Keep looking at the pages on
www.google.com.