BSNL - prepaid sim
Account balance alert is not coming for my sim card

My mobile no: 9440966338. from Tirupati, andhra pradesh...

In some of the BSNL Prepaid sim cards, account balance and last call charge are coming as a message alert just after the call. In my mobile this does not happen. Since it is a useful feature I would like to enable the same in my mobile. One of the customer support employee at BSNL said that this facility will available only for few series of mobile numbers. I don't think this is not genuine answer. Please advice how I can make available this feature in my mobile.

Thanks