The first step that you have to take is to take out the print outs of the transactions that appear on your bank statement in correspondence to the transfer that you made under the influence of the fraudulent call.
Next you have to file an E-FIR with the Cyber Cell/Concerned police station.
On moving the FIR, an investigating officer shall be appointed by the police station in-charge who will investigate the matter on the basis of your bank entries and the concerned fraudster shall be traced by his IP Address or bank account and hopefully caught.
You should do this without wasting any time.
Time consumed in such cases depends on the action of the police and how intelligent is the fraudster.
You are advised to engage a local lawyer who knows his way through the police and see your case in the right direction!