Here's the step to setup modem BandLuxe C100 WCDMA on your Ubuntu.

1. You need to install package wvdial first.
Check your system in terminal using :
#dpkg -l | grep wvdial

2. Make sure you're disconnected from ethernet / LAN
Stop the network in terminal using :
#/etc/init.d/networking stop


3. Plugin the modem BandLuxe C100 into USB Port

4. Open terminal and login as root

5. Make a symbolic link from ttyUSB0 to modem
#ln -s /dev/ttyUSB0 /dev/modem

6. Type this as root :
#wvdialconf

7. Edit file /etc/wvdial.conf
Phone = {your ISP dialup #}
Password = { your ISP login password }
Username = { your ISP login name }
Save the file

8. Connect to ISP using this command in terminal :
#wvdial
If you can see the IP WAN and DNS address then the connection is successful.
Try using ping test to a website.

9. To disconnect from the ISP hold and press Ctrl+C on the opened terminal.