Mobile number portability (MNP ) has finally come to India and for that the first thing you need is a porting code which is given by the existing operator ( Vodafone, Airtel, TataDocomo for example ) of yours. Since this is a competition and no operator wants the customer to leave it is possible that operators may play foul and not send you the porting code or might delay it a lot.
In case your operator is not sending u the porting codes, You can make a complaint at
Also here is list of Telephone numbers and email id of Department of Telecommunication. | Thanks ShriRam