Sunday, February 17, 2013

Using a 3G USB stick Vodafone Globetrotter K3760 - Option 431 on GNU/Linux

These days, I need a 3G USB stick to access the internet.
The USB stick provided by my company is a Vodafone Globetrotter K3760. It is actually the 3G card from Option N.V, the Option 431 model.

When I tried to plug the stick in my Ubuntu, nothing happened. This was because UDEV actually didn't know the device yet.

There is not a lot of comprehensive information on the internet about it (I haven't been able to find something at least), therefore here is, I hope, a simple and straightforward to get things up and running.

It is a three steps process:

Add a new udev rule

Create a new rules file in the udev configuration directory.
sudo gedit /etc/udev/rules.d/vodafone.rules

Then, copy paste the following in the file:

# Option N.V. Globetrotter HSUPA Modem (K3760)
SUBSYSTEM=="usb", ATTR{idVendor}=="0af0", ATTR{idProduct}=="7501", RUN+="/usr/sbin/usb_modeswitch --default-vendor 0x0af0 --default-product 0x7501 --message-endpoint 0x01 --message-content 55534243785634120100000080000601000000000000000000000000000000"

Basically, it teaches udev about our device's idVendor and idProduct so it can recognize it and tell it to execute usb_modeswitch with some parameters specific to our 3G USB stick.

Therefore, if you have another 3G USB device, you need to find the good:
  • idVendor
  • idProduct
  • message-endpoint (if there is one)
  • message-content
You can find a list of such informations in the usb_modeswitch sources or online here:

Also, some devices may require to add --reset-usb 1 argument to the usb_modeswitch command line.
Syslog is your best friend in this case.

Restart the udev service

From a terminal, enter the following command:
sudo service udev restart

You can also restart your computer of course...

Plug the 3G stick and configure the network manager

Once udev has been restarted, you can simply plug you 3G USB stick into your computer and wait for the PIN prompt.
You can also configure a broadband access using the network manager since the device is now correctly detected.