Block unwanted calls in India by National “do not disturb” DND

   First join the do not call registry.
http://ndncregistry.gov.in/ndncregistry/index.jsp.
    This will maintain all subscribers list who have opted for “do not disturb service”.A telemarketer will lose his license or face a fine of 500 Rs per call or sms he sends you after you register to DND service.
Stop unwanted calls in Airtel:
Airtel postpaid and prepaid mobile users sms “START DND” to 121 and broadband and landline customers call 121.
Stop Unwanted Calls on Vodafone:
You need to send a SMS ACT DND to 111
Block calls from Reliance:
http://www.reliancecommunications.co.in/Communications/Rm/rm_index.html and fill up a form to register to dnd.
Stop Calls on Idea Callular -
Call up 1909 to register to DND.
or SMS “START DND” to 1909 and for un-listing / de-activating DND send “STOP DND” to 1909.
Tata Indicom:
http://www.tatatele.in/dnd/DNDAction.do use this link to activate DND.
Tata Docomo:
If you want to register yourself on the NDNC registry, simply SMS START DND to 1909 (toll free) and in case you want to de-register yourself from the NDNC registry SMS STOP DND to 1909 (toll free).
BSNL:
http://pdnc.bsnl.co.in/
Interactive Voice Response System (IVRS) – Call Toll-free number 1909 and follow the IVRS instructions for registring/de-registering.
SMS – Send SMS to 1909 with keywords ‘START DND’. It will be registered. For de-registering SMS ‘STOP DND’ and it will be dergistered.