Mobile Broadband USB modem in Ubuntu

1. Open a terminal

2. Install udev-extras from the standard Ubuntu repositories:
    sudo apt-get update && sudo apt-get install udev-extras
    or
    sudo apt-get update && sudo apt-get install udev

3. Add a custom udev rule for the Huawei E1550 by typing this line:
    echo 'SUBSYSTEM=="usb", SYSFS{idProduct}=="1446", SYSFS{idVendor}=="12d1", RUN+="/lib/udev/modem-modeswitch --vendor 0x12d1 --product 0x1446 --type option-zerocd"' | sudo tee  /etc/udev/rules.d/45-huawei1550.rules

4. Configure the Mobile Broadband on Network Manager. (right mouse the Network icon near the volume icon).

5. Select Mobile Boardband -> Add

6. After added, restart the pc.

7. Cheers...