I installed Ubuntu 12.04 LTS on an HP pavilion dv6 laptop alongside Windows 7.
I am not able to connect to internet via Airtel 3G USB dongle. I tried editing the network connection and am still unable to connect to Internet. Apart from that, while installing Ubuntu certain firmware updates we needed and I skipped that step since I couldn't connect to Internet.
Here is how it worked for me:
Properly insert your dongle to the USB port; don't worry if it's not detected by Ubuntu.
Go to: Network Connection -> Mobile Broadband -> Add
Now there are 5 simple steps; select the natural options:
Since in my case it was without password, I din't have to do any extra settings related to ip address or any setting in the final dialog.
First connect to some LAN or Wi-Fi and update your packages. Then, when you plugin the dongle, the network connections should show Enable Mobile Broadband. Then click on Edit connections -> Mobile Broadband -> add. Select country, then operator and so on. Try this and get back.
This has worked for my Reliance 3G Dongle.
Copy the install_linux folder from the usb dongle to your desktop and then run the installer script
Taken from: http://www.tuxtrix.com/2013/06/how-to-install-airtel-mobile-broadband.html