If you are getting unwated calls or SMS to your mobiles,you
can register your number with NDNC which will stops all these spams.
To register your mobile in NDNC service,
Send SMS with message START 0 to 1909 or call 1909 and
follow instruction.
You can stop call by category also. Below is the category
code
1. Banking/Insurance/Financial products/credit cards
2. Real Estate
3. Education
4. Health
5. Consumer goods and automobiles
6. Communication/Broadcasting/Entertainment/IT
7. Tourism and Leisure
For example if you want to stop call related to real estate
you can send SMS with code 2
ie STOP 2 to 1909