Vikesh These mobile phone networks are developing more and more ways to develop advertisement and one of it's product is flash messages. These messages actually cover up your whole screen which is very embarrassing and remains a chance of balance deduction with just pressing of OK. Well first of all let me tell you that you don't need to activate DND - Do not disturb service to stop this and the solution is within the phone. I got many complains of you to solve this and I found the most of the problems arose in Vodafone and Airtel networks.
I am explaining here with Vodafone go to - sim services - Flash - Activation - Deactivate. and you are done , easy na, yes but very effective trick. For airtel do the same process but inspite of Flash option their is Airtel Power.

 Mukesh Vikesh Uninor plz?