Trick to block incoming calls in bsnl

Here iam sharing a simple trick to block incoming calls in bsnl 2g&3g.
Actually this is not a trick,but we can block all calls when needed .
Here we are using a simple technique which will cause money loss to those who tries to call us, by diverting the call to another number.
Now you may be thinking that it will cost you some money to divert calls to another number, but what about diverting the call to customer care?
It will cost you nothing and it costs ur opponent.
In order to activate this call divert trick 
just dial :  *21*+919400024365#
You can deactivate whenever you like.
To deactivate dial : #21#