Those of you who have been fed up with those irritating calls from telemarketers must surely have activated DND service by now. I did too. In India, you can activate DND by sending the SMS "START DND" to 1909.
Vodafone customers also have a feature by which you can send an emergency message. You're supposed to use it when you have Zero balance. Using this feature you can send Vodafone a message and vodafone forwards that message to your friend as a request to contact you asap.
Now the problem is that if you have DND activated on your mobile you will be prevented from recieving these emergency messages. By some fluke of law, the emergency message is regarded as a tele-marketing message and thus blocked.
So if you've got DND activated, be aware that it'll also prevent emergency messages from reaching you.