Small tutorials & scripts that can be used as references for connecting usb 3g/4g modem, in OS linux such as Raspbian, Ubuntu and other Debian's variants.

• Ensure that wvdial, ppp & usb-modeswitch have been installed. Run sudo apt-get install command for installing them, if you have not done it before.

• Plug-in your USB Modem, wait for few seconds then run lsusb command. Notice the manufacturer of your modem is displayed within the list. Make note the vendor id : default product id code that appear before the manufacturer's name. E.g. 05c6:f000
• Download & untar usb-modeswitch-data from this following url: http://www.draisberghof.de/usb_modeswitch/. Make note the path of folder where contains the extracted files.
• Clone this repository into your home folder.
• Copy the mswitch.sh & 4glte.sh script files into the folder of untar-ed usb-modeswitch-data and ensure that the copied files can be executed (run chmod 755 command against them, if they are not executable. ). To make it easier executing these scripts later, create links against them using ln command, e.g. ln -s mswitch.sh mswitch, ln -s 4glte.sh 4glte.
• Open the mswitch.sh file, changed the USB_MODEM_VENDOR_ID & USB_MODEM_DEFAULT_PRODUCT_ID entries with vendor ID & default product ID that you have noted in prior step. Save the changed file. Changed the mswitch_path variable with the location of untared usb-modeswitch-data directory.
• To ensure 4glte.sh can be executed from anywhere in the machine, concatenate the location of copied script files with the current $PATH variable. You could do it by modifying .profile file inside your $HOME folder. Here is the example of the modified .profile file:

export USBMODEM=$HOME/usb_modeswitch_data
export PATH=$PATH:$USBMODEM

Save the .profile file and run this command to apply the changes source .profile

• Run 4glte command to begin connecting to internet using the plugged in USB Modem.
• To disconnect the modem, run this command 4glte disconnect.

• Copy the 4glte script inside cloned repository's etc/init.d folder, into your machine's /etc/init.d directory.
• Ensure the copied 4glte script is executable. Run sudo chmod 755 /etc/init.d/4glte command to ensure this.
• Open the copied 4glte script as superuser & edit the entry which point to the directory location of where you put the 4glte.sh file at. Save the changes.
• Run sudo update-rc.d 4glte defaults to register the script as a startup script.
• Run sudo update-rc.d -f 4glte remove if you want to de-register the script from being executed when the system boot.