Comment 2 for bug 574119

Try to use "lsusb" in terminal.

If you find string "12b1:1446" and followed by modem's brand, then this trick should work for you.

Open Gedit, copy this text :

----------BEGIN----------
ACTION!="add", GOTO="huawei_zerocd_end"

SUBSYSTEM=="usb", ATTR{bDeviceClass}!="ff" ,ENV{DEVTYPE}=="usb_device", GOTO="huawei_zerocd_disable"
SUBSYSTEM=="scsi", ENV{DEVTYPE}=="scsi_device", GOTO="huawei_zerocd_disable"
GOTO="huawei_zerocd_end"

LABEL="huawei_zerocd_disable"
ATTRS{idVendor}=="12d1", ATTRS{idProduct}=="1446", RUN+="modem-modeswitch -v 0x%s{idVendor} -p 0x%s{idProduct} -t option-zerocd"

LABEL="huawei_zerocd_end"
------------END------------

Do not copy the begin and end line, of course.

Save it on your desktop, named "15-huawei-e1551.rules" (I know, your modem is E1550, but this should work) and quit Gedit.
Press Alt+F2, type "gksudo nautilus", this will launch nautilus in Super-User mode.
Now open "/home/username/Desktop", select the file, right-click it, choose copy.
Finally, open "/etc/udev/rules.d" and paste it there.
Restart your computer, and then plugin your modem.
Type "lsusb" again in terminal, if the string change to 12d1:1001 followed by your modem brand, you should be able to use your modem.

Source : https://launchpad.net/bugs/401655