This only applies to BSNL connections which use username – password. For others generally no configuration is required, everything is automatic.
1. (Left) Click on the network icon on the top panel and then choose “Edit Connections”
2. Move to the “DSL” tab and click “Add”
3. Fill in the details as in the following figure. Don’t forget to tick the check boxes.
4. Click save, enter your password if asked for, and you are done!