Open DNS works for my BSNL that much i know, atleast was proven yesterday at home. OR same time sea line issue was repaired
will check again today evening and see. In BSNL i have noticed there will be an
marginal improvement in speed during normal times (multiple test with speedtest.net). Dont know about other DSL's.
They do have some inbuilt restrictions and blocks where by warning pages are issued for certain sites which are fraudulent in nature.