Call Barring is a service that allows subscribers to stop all calls (either incoming or outgoing) on their sim and all the networks use the same codes which is listed below:

Call Barring         
Description USSD
Incoming Calls *35*0000*11#
Outgoing Calls *33*0000*11#
Cancel All Call Barring #330*0000#


NOTE:
* the default PIN is ‘0000'.