Activate DND (Do Not Disturb) and Check Status

Few months ago, I moved from Airtel to Idea and suddenly I started getting a lot of telemarketing calls. It wasted a lot of my time as I was under the impression, DND was active on my account.
It turned out that Airtel removed me from DND when I decided to get away from them. Among telemarketing calls, there were calls from Airtel also.

Check Status

You may call 1909 to enquire current status and know your NDNC registration date.
I prefer the online way. You can check DND status online using this official link http://www.nccptrai.gov.in/nccpregistry/search.misc for any number!
Below is what I saw for my number:

As you can see, DND was de-activated on my number on January 9, 2014. I switched from Airtel to Idea around same date.
Does it happen always? Do you expect DND to get deactivated when you switch from one provider to another provider? Not sure. I have one more number and when we switched it from BSNL to Idea, it’s DND remained active!

If you are getting calls from number starting with 0140 then you may not be on DND or getting a call from somebody who doesn’t respect DND!

Activate DND (Do Not Disturb)

As I was removed from DND, I had to activate it again.

To Stop ALL Calls

Send SMS with the message Start 0 to 1909.
You can will get a reply by SMS asking for confirmation. Send another message with a letter Y to confirm.
If you don’t like typing, you can also call 1909 from your mobile and follow instructions.

To allow calls of particular category

Category selection 0 in Start 0 blocks all categories. If you wan’t to allow some categories only, below is a list of category numbers.

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

To allow category specific calls, type Start 1 for Banking/Insurance, etc category.
You can specify multiple category as well by typing Start 1,2 in SMS.

Register a complaint

If DND is active on your number and you are still getting calls, you can register a complaint about calls to your service provider.I was under the impression that complaints need to be made directly to TRAI or some government authority.

By SMS

You can send a SMS to 1909 in following format to register your complain.

the unsolicited commercial communication, XXXXXXXXXX, dd/mm/yy

Or another format:

COMP TEL NO XXXXXXXXXX, dd/mm/yy, Time hh:mm

Replace XXXXXXXXXX by number from which you received call and dd/mm/yy and hh:mm with date & time, respectively.

Check complaint status

You will get a complaint number, whose status can be tracked online from http://www.nccptrai.gov.in/nccpregistry/UccSearch.misc
Android App
There is an Android App to register complains easily here. (thanks anantshri)

Important Notes

If you are moving from one service provider to another service provider, under MNP (mobile number portability) scheme. and you suddenly starts getting a lot of telemarketing calls, it’s better to check your number’s DND status online.
Source: Most info in this article can be found on official site - http://www.nccptrai.gov.in/nccpregistry/