I have a USB 3G mobile modem (ZTE MF626) and I'm having trouble to use it on ubuntu (11.10). The device is not recognized when plugged. But the LED light on the modem is on, and, if you insert a memory card on the slot (MSD), the device is recognized. I've checked on Windows, the modem internal storage device is CDFS formatted.
I already searched the web about it, but the most problems are about connection and configuration (the modem is being recognized).