Do you mean the IMEI? If that is what you mean, then the most you can do is ask Qtel/Vphone to BLOCK that handset for you. This means that nobody else can use it.

If you go to police, then police can force Qtel/Vphone to handover the phone number and other details of the person who is using it now... if someone else is using it. BUT it is unlikely that the police will go to such lengths in order to try and recover a handset. :-(

Good luck.