These are the steps which I used to setup airtel adsl in linux.
Hook adsl modem to NIC through ethernet port.
Boot to linux
Make sure NIC is installed in Linux. If you don't know how to do it then check linux distro forum / support.
Login to system with 'root' user.
At terminal type the command 'adsl-setup'
Enter the details as prompted.
At the end you will see the commands to dial to internet with your ppp (broadband) account.
If your modem is configured to auto dial then you don't need to run the command adsl-setup.
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