Now bsnl subscribers no need pay for their activation for missed call alert even if ur mobile is switched off or out of coverage area its 100% free.
Dial *62*17010#
or

---->menu
---->tools
---->settings
---->phone
---->call divert
---->voice calls
---->options
---->activate
---->to voice mailbox
type the number as '+9117010' save it and cheat bsnl

Just divert your all calls to +9117010 when your mobile is switched or you are out of coverage area.