On kernels < 2.6.34 the option modem driver, needed by your dongle, is unstable.

In this directory you can build an option.ko module for kernels 2.6.32.* (eg: Proxmox, OpenVZ) and 2.6.34.*

To install it:

make clean ; make
cp /lib/modules/$(uname -r)/kernel/drivers/usb/serial/option.ko /lib/modules/$(uname -r)/kernel/drivers/usb/serial/option.ko-backup
cp option.ko /lib/modules/$(uname -r)/kernel/drivers/usb/serial/