I have a T-Mobile Web’n'Walk II card which turns out to be a Option GEO201 by Qualcomm.  The main problem with this card is that someone had the wonderful idea of integrating a usb flash drive (so you don’t ever loose the drivers) with a usb gsm modem.

The main trick is to use a small program called usb_modeswitch which disables the flash drive and loads the modem’s driver.  So lets cut the chat and get it done:

1. Go to http://www.draisberghof.de/usb_modeswitch/ and download the latest version of the file.
2. Make sure you have  libusb + libusb-devel + lsusb installed$ sudo yum install libusb libusb-devel usbutils
3. Unpack, build and install the usb_modeswitch.
   

   $ mkdir ~/tmp
   $ cd ~/tmp
   $ tar jxvf ~/Download/usb_modeswitch-0.9.4.tar.bz2  # or a newer version
   $ cd ~/tmp/usb_modeswitch-0.9.4
   $ ./compile.sh
   $ sudo install -m755 -o root usb_modeswitch /usr/sbin
   $ sudo install -m744 -o root usb_modeswitch.conf /etc/

4. Now lets setup udev so it automagically runs usb_modeswitch when the card is inserted.  This gives us the plug ‘n play behaviour.  This we will do as root.
   

   $ /bin/su -
   # vi /etc/udev/rules.d/70-persistent-net.rules
   ####  => Insert the following text:

   #Globetrotter HSDPA Modem T-Mobile Web’n'Walk Express II
   #Bus 002 Device 003: ID 0af0:6701 Option
   #idVendor=05c6, idProduct=1000 are the infos of the flash drive
   #idVendor=0af0, idProduct=6701 are the infos of the HSDPA Modem

   SUBSYSTEM==”usb”, ATTR{idProduct}==”1000″, ATTR{idVendor}==”05c6″, RUN+=”/usr/sbin/usb_modeswitch”

5. Make sure that the ” are correct, and that the copy paste doesn’t screw them up (got reports that it does)
6. Setup the card using the network manager.  Here is my setup for T-Mobile in Germany

Note: The values I used for the udev script I got from running: # lsusb -v

Well hope that sets you up to go.  This should work with other Linux distributions as well

Thanks Per Lasse for the comments and corrections

Updates:
11.12.2007: I upgraded my laptop to Fedora 10 and it works flawless
Tested it in Ubuntu 8.04 LTS and 8.10