It was an honest, mundane customer service job, advising the customers of Delta Air Lines on such matters as lost baggage and frequent-flier miles, for a mediocre monthly salary of $150. He was sitting on a waiting room sofa when he picked up The Times of India and read that 700 of his co-workers had been detained the night before.

The first person he contacted was Ms. Broder, to tell her that the raid had hit the same operation he had described to her. That night, he and Mr. Dubey, who had left the Mira Road center after contacting Ms. Broder, celebrated over drinks.

“We brought it down,” Mr. Dubey said. “It started out as fun, then it got boring, then we truly understood the good and dirty parts of the job. Then we decided to bring it down.”

Whistle-blowers’ motives are often murky, and in their early conversations, Ms. Broder wondered fleetingly whether the two friends were calling on behalf of the scheme’s organizers to determine what American investigators knew. In an interview with The New York Times, the two men acknowledged being fired from the call center after getting into an altercation with co-workers.

Their claim to have brought down the center is unfounded, according to Indian and American investigators, who said that the raid in Thane was carried out entirely by the local police, without assistance from American officials. The Thane police said their informant was not employed by the swindlers. The raid was international news, and in the weeks that followed, the number of fraudulent I.R.S. calls to Americans dropped 95 percent, according to the Better Business Bureau.

But those who believe that the drop is permanent should consider this: In the weeks after Mr. Poojary and Mr. Dubey left the center, several lucrative job opportunities were presented to them. Each involved a phone scheme targeting Americans, they said. There was the Viagra scam, in which callers offered to sell cut-rate Viagra; there was a low-interest loan scam, in which people were asked to deposit $1,000 as proof of income. There was a tech scam, which warned Americans that their computer had been infected by a virus, and an American Express scam, which involved gathering personal information to break through security barriers on online accounts.

“Even if you shut down 400 buildings in India, it will not stop,” said Mr. Dubey, now known by his Delta clients as Jacob Davis. The two friends say they have given up on the notion of getting rich quickly, or of being paid by the United States government for the information they provided.

It has been replaced by a new hope — that, perhaps as a result of the public service they have provided, they will be granted visas to the United States, the home of so many of their favorite things: “The Fast and the Furious,” Vin Diesel and Robert Downey Jr. “I’ve spent so much time getting to know it, familiarizing myself with its states, talking to its people,” Mr. Dubey said. “I feel a bond.”