An internet-based call were made to many phone numbers simultaneously, called 'blasting' in technical terms, and the potential victims were made to listen to it which allegedly used to threaten them, they said.
"Some of the victims got frightened with this and called back. When the call was returned, the call centre executives, through the phone number of the caller, surfed through the websites (having information about people's name, addresses and other details) in real time to understand the paying ability of the person at the other end," a police official told PTI.
"During investigation it was revealed that the scam's alleged mastermind, Sagar Thakkar alias Shaggy, and his associates used to blast the VOIP calls from Ahmedabad," the official said.
These calls were made with Direct Inward Dialling (DID) by which at a time 10 US citizens could get calls with the help of a software, he said.
More From This Section
The call was spoofed and contact numbers similar to those in United State's were displayed on the cell phones, by which the American citizens were made to believe that it was a call from the US Tax Department.
The 'dialler' used to asked the victim if he wanted to resolve the issue. If he agreed, then the call was transferred to his senior - the 'closer'.
At the supermarket, the victim was instructed by the
'closer' to purchase 'gift cards' and tell their 16 digit number to him. The 'closer' would then pass this 16 digit number to Thakkar.
Thakkar then used to call his vendors in the US and asked to deposit the gift cards worth thousands of USDs. He would then allegedly receive the money through 'hawala' in Mumbai and Ahmedabad, the official said.
Police had raided the Universal Outsourcing Services, on Mira Road in neighbouring Thane district, among six other call centres during the midnight of October 4-5 and got the data of thousands of US citizens who were cheated.
From June 1 to October 4 this year, Thakkar allegedly collected USD 18 lakh from just one call centre, the police official told