Nearly an hour into the phone call, the woman began to get suspicious.
The man on the line said he was with the Internal Revenue Service and that she owed a penalty for tax fraud. But to make the payment, he told her to drive to a nearby Food 4 Less grocery store in suburban San Diego and purchase an iTunes gift card.
Twice he said she owed "1,000 rupees," before correcting himself to say $1,000.
Even the name he gave, Daniel Parker, sounded odd. He spoke with a foreign accent and mangled basic phrases.
"Your name is Daniel Parker? Are you sure?" she finally asked.
"Yeah, ma'am," he replied. "I am sure."
But it was too late. The 29-year-old National City woman had already shared an iTunes card number worth $500 – becoming one of tens of thousands of Americans drawn in by an extensive, years-long scam in which callers from India pose as IRS agents to extort money from taxpayers.
Indian call centers have built a reputation for handling customer service and tech support inquiries for major U.S. companies. But in recent years, investigators in the United States, Canada, Britain and other countries have traced several organized phone frauds – involving callers posing as computer technicians, debt collectors, immigration officials or tax agents – to Indian call centers.
On their surface, little sets the illicit call centers apart from legitimate ones. They operate almost in the open, using the same corporate-style office spaces and recruiting from the same vast pool of English-speaking college graduates — allowing the crimes to persist for years.
This year, the Federal Trade Commission described Indian call centers as "the source of various impostor frauds that have reached consumers throughout the English-speaking world."
Last month, police in the northern Mumbai suburb of Thane (pronounced THA-nay) raided three office buildings suspected of being used to make the fraudulent IRS calls and rounded up more than 700 people for questioning. At least 70 remain behind bars as investigators have expanded the probe to include dozens of call centers in multiple Indian states.
Weeks later, the Justice Department announced the indictments of nearly 60 people in India and the United States for involvement in shady call centers that had conned more than 15,000 Americans out of hundreds of millions of dollars since 2012.
Among those indicted for conspiracy, fraud and money laundering is the suspected ringleader of the Thane operation – Sagar Thakkar, also known as Shaggy, a flamboyant twentysomething with a taste for ripped jeans and fast cars, who is believed to have fled India as police closed in on his business.
The scheme – part of what the IRS described in 2014 as the largest phone fraud to target American taxpayers – has exposed a dark side of India's $30-billion call center industry, a symbol of this booming country's information economy and one of its biggest exports to the West.
"It has blighted the image of India," said Parag Manere, deputy police commissioner in Thane. "Someone who does this kind of thing, they will not be tolerated."
Yet the Thane police investigation and the federal indictment unsealed in late October showed how the scam went on for several years despite growing concern in both countries.
The Oct. 4 raids in Thane led police to the headquarters of the operation in Ahmedabad, in the western state of Gujarat, which has a large diaspora population in the United States. There investigators found computers with sophisticated "call blasting" software that was used to place thousands of voice mails to numbers in the U.S.
The messages would warn the recipient that he or she was suspected of tax fraud and order the person to call a U.S. number – routed to one of the call centers in India.
Authorities believe dozens of calls a day were fielded at the offices set up this year outside Mumbai, India's commercial capital, whose large numbers of jobless English-speaking college graduates were prime candidates for recruiters.
Police said entry-level callers were paid about $300 a month, plus commissions — a typical call center salary, though far less than the amounts they extorted from individual victims.
"Any large country where the employment opportunities are few but the number of available graduates is high, you will always have the risk of illicit activities," said K.S. Viswanathan, vice president of industry initiatives at Nasscom, an industry group that has worked with U.S. authorities to combat call center fraud.
In Thane – a once-sleepy backwater now exploding with high-rise apartments and office blocks – most of the callers operated out of a nine-story tower of glinting blue glass called the Hari Om IT Park. When it opened this year, police said, suspects used the cover of an outsourcing company and signed a lease to occupy six floors, installing desks and partitions to house hundreds of employees.
Starting in July, large groups of employees — mostly men in their 20s — began arriving around 7 every evening, typical working hours for call centers that deal with customers in the United States. They would wrap up around 6 a.m. and return that night to start a new shift.
"There was nothing suspicious that we saw in that time," said Prem Bahadur, the building's caretaker, who lives in a small room on the ground floor behind a hulking generator. "It looked like a normal call center."
A second office opened a month later, in a basement below a bank branch. The 4,800-square-foot space was subleased from a tenant who had a five-year lease, and representatives of the landlord said they did not know the identities of the tenants.
Authorities believe these two offices and a third nearby raked in between $150,000 and $225,000 every day.
"They knew they were cheating people," Manere said. "But perhaps they didn't care because the victims were foreigners."
At one of the offices, police found a six-page script used to train employees. In long, convoluted passages filled with gaffes – one police officer said the fast-talking Indian callers sounded "like parrots" – it demanded the target make an immediate payment or police would show up "at your doorsteps" within 30 minutes.
If the person sounded ready to pay, the call would be handed to a more experienced "closer" to complete the deal. But if he or she expressed suspicion, the script suggested a sharp response:
"I will promise you will gonna lose everything what you have and you will end up paying bills to IRS to your rest of your life."
"I thought they were prank callers because of the kind of language they were using," said Anant Dhillon, an Indian immigrant in Victoria, British Columbia.
Returning a message from the "Canadian Revenue Agency" in April, Dhillon, a bank employee, was connected to a call center that he assumed was near Mumbai, because he could make out voices in the background speaking Marathi, the local language.
"They said I owed thousands of dollars. But I said I only make about $40,000 a year so there must be something wrong with your numbers. Then the guy started swearing at me in Marathi and Hindi."
Dhillon hung up and reported the call to local police.
But many others were taken in. One Indian immigrant in Tustin contacted Thane police to say his 75-year-old father had been conned into paying $2,000. Another elderly American suffered a fatal stroke after being threatened on the phone, police said.
Some victims described in the federal indictment paid tens of thousands of dollars using dozens of gift cards, such as iTunes cards.
Once they obtained the card number, scammers transferred the money to a prepaid debit card, which they used to purchase a money order, authorities said. That money was deposited into a U.S. bank account and wired to India using the informal hawala money transfer system.
U.S. and Indian agencies have made arrests before in similar cases. Last year a Pennsylvania man, Sahil Patel, was sentenced to 14 years in prison for his role in an India-based IRS scam, though the kingpins remained at large.
The Thane bust could be the most significant yet. The Better Business Bureau, which used to field approximately 200 reports of tax scams every week, said that after the arrests in India it received just 11 complaints in a week.
The impostors seemed unaware the police were closing in. Speaking to the National City woman on Sept. 24, a caller in Thane insisted she leave her office immediately to make a payment, according to a recording police provided to The Times.
The woman wondered how she could owe a tax penalty, saying she had earned less than $20,000 in 2015. But the caller's demands only grew more specific. She had to keep him on speakerphone while she drove to the Food 4 Less, he said, and when she went inside to buy the iTunes card.
"Just keep the phone in your pocket," he said.
"I can't," she replied, sounding worried. "I don't have any pockets."
It was agreed that she would keep the phone in her hand.
Twenty minutes later, the $500 transaction completed, the caller asked for an additional $500, saying that would make her "free from the IRS."
She had rent and car payments due, but agreed to pay the following week. Satisfied, the caller asked if he could give her a compliment before hanging up.
"You have a sweet voice," he said.
Ten days later, the police swooped in.
Follow @SBengali on Twitter for more news from South Asia
Special correspondent Parth M.N. contributed to this report.