Discussion on:

How to reduce Service desk calls

I need to know the best practices to reduce helpdesk/ service desk calls ,which are being implemented in any organisation

That is try to keep those in your organization informed. Pre-announce any upcoming changes, up-dates, etc., before they are implemented. Publish simple user guides and tips, to preempt common user calls to your help desk. Sometimes a simple FAQ list on known issues helps. Try to anticipate common trouble call issues, and 'Broadcast' solutions before they become trouble calls. Be 'Proactive'. The time spent doing so will be recovered in the reduced time spent resolving known issues, one user at a time.
Doing so also demonstrates the worth of your Help Desk program.