Did you run this command?
Can you see your modem in the list?
When you run following command
# wvdialconf /etc/wvdial.conf
Do you get this error?
Sorry, no modem was detected! Is it in use by another program?
Did you configure it properly with setserial?
Please read the FAQ at http://open.nit.ca/wiki/?WvDial
If you still have problems, send mail to <email@example.com>.
Have you added vendor id and product id of your usb modem in modprobe?
# sudo modprobe usbserial vendor=0xVID product=0xPID
You will get vid and pid from output of command lsusb
If not add them and run
if it shows modem name like /dev/ttysomething/
it means it is connected. Make a new connection using mobile broadband.
Try to connect to internet.
Now paste the out put.