ZERO dial is required for landline to STD calls and Mobile numbers and DOUBLE ZERO dial is required for ISD calls. By default VOICE MAIL, CALLER ID (also called CLIP) and LANDLINE to Local LANDLINE are free. CLIP service is by default not provided for BUSINESS ACCOUNT.
By default for new connection 0 and 00 dial is disabled for customer safety. If you have applied for STD and ISD facilities at the time of subscription then after 24 hours of installation STD and ISD will be activated. If there is no 0 and 00, call customer care center and register your complaint.
Latest update on 4 Dec 2015: STD and ISD is activated, Field engineer should verify that STD and ISD is working before leaving customer place.
If you are existing customer but with upgrading and migrating option then call customer care center and register complaint for the activation of STD and ISD facilities.