BSNL broadband does not work with Ubuntu 14.04

[gambit]

Gambit - that is what happened ultimately. I had to enter manually enter IP address and log in. The question is why is that ? Why am I unable to access DHCP ?

I am unable to ping 192.168.1.1 on Ubuntu.

Reason you can't access DHCP is it is turned off on your modem/router, turn on DHCP from modem page.
Are you unable to ping 192.168.1.1 even after manually entering IP address?
After turning on DHCP, you will have to set manually entered IP address back to Automatic to see if DHCP is working.