The Syrian businessman was enjoying a much needed holiday in Turkey when the phone call came from the tax inspector of the Islamic State.
His business partner in Raqqa had been arrested, the inspector told him, and he would not be released until his company paid the $100,000 (£65,000) it owed the "Caliphate."
"They told me that because I have a lot of money, I have to pay my share," said Ammar, who asked that his real name not be used. "They analyze your income and take a percentage."
As the Islamic State, also called ISIS or ISIL, works to establish its empire, the jihadists have become fastidious bureaucrats: imposing taxes, paying fixed salaries, and imposing trading-standards laws in a bid to create a healthy economy that will sustain the group's autocratic rule.
Yet despite brutal punishments for those who break the laws, many Syrian businessmen see ISIS as the only option when compared with the anarchy that prevails in areas controlled by other rebels, including Western-backed groups.
Ammar, who deals in cars, houses, and poultry, is largely secular and privately despises the jihadists (he refers to the ISIS-held "capital" of Raqqa as "the big prison").
Yet he acknowledges that he now works almost exclusively in ISIS-controlled areas, having had $150,000 worth of stock stolen by a gang in turf run by another armed faction. Likewise, when he traded in areas controlled by the Syrian government, he was detained by a pro-regime militia, which demanded a bribe of $25,000 for his release.
While ISIS charges zakat, the alms payment in Islam — essentially an income tax — to those residents who can afford it, Ammar said businesses were protected from theft and corruption.
"When I take chickens that I have bought from farmers in the rural areas to Raqqa the first thing I have to do is go to the zakat office and pay the standard 2.5%," he said. "They then give me a voucher that allows me to sell the produce in the city."
The model is being applied across ISIS territory in Syria and to such a degree that businesses are now choosing to move their industry into ISIS areas.
The owners of factories in Sheikh Najjar, an industrial estate north of Aleppo city, and now a frontline, have moved to ISIS-controlled Minbij, several residents and business owners told The Telegraph.
"You can find everything from cotton to iron and plastics being processed here," one factory owner said by phone.
In part this is because the Syrian regime has bombed ISIS areas less frequently than those of other rebel groups. But also, all the residents agreed, it is because there is more efficiency and less corruption.
One Syrian aid worker recounted going to the market in Minbij that sells oil collected in ISIS-controlled fields: "There are hundreds of pickup trucks filled with barrels. These barrels are labeled with different colors according to the quality of the benzene inside."
As ISIS, many of whose leaders are from Iraq and Tunisia, tries to lay down roots in Syria, local residents have been allowed to maintain public services.
Teachers may continue to work, providing they agree to instruct the new curriculum, which bans subjects such as English and science, and is heavy on Sharia. Doctors and engineers, particularly those managing the ISIS-controlled oilfields, are paid handsomely — at least double, and often several fold the salaries offered in other parts of the country.
With the zakat offices run by locals, they "know how much wealth their neighbors have," and so they can insist on the "correct" tax percentage, one Raqqa resident said.
"One of them knocks on the doors of homes and demands the payment; they give you a receipt with the ISIL stamp," he said, asking, like the others in this article, not to be named, as speaking to journalists is considered a crime by the extremists.
For all the taxation, the emerging "Caliphate" remains a place that favors the rich.
The jihadists have mostly eschewed the demand in Islamic law that the zakat be used to sustain the poor, instead using the funds to buy weapons and inflate the salaries and benefits of their own fighters.
A female resident of Minbij recounted to The Telegraph how the restaurants and shops are frequented almost exclusively by ISIS fighters, with most of the civilian population unable to afford them.
In Raqqa, residents said money had been spent on new medical equipment that wasn't available to locals.
Ammar the businessman acknowledged that his best business was selling cars to jihadists, many of them foreigners, who are flush with cash.
Hassan, a satellite installation engineer in Raqqa who came to Turkey only last month after he was wounded in a regime airstrike said: "If you have some money, and can keep your mouth shut, living there is OK."
For most Syrians, the price paid for this modicum of stability is repression.
The jihadists' extreme version of Sharia law imposes a culture that is inimical to that of most Syrians, whose Sunni population overwhelmingly subscribe to a moderate interpretation of Islam.
Now women cannot leave the home unaccompanied and must wear the face-covering niqab. They cannot interact with men who are not close relatives or their husbands. Men should wear pants that fall above the ankle and long beards. All animal products entering the city must be halal. Films, music, and all kinds of games are banned.
The tactics used by the jihadists to enforce their order are not dissimilar to those used by the regime: spies, detentions, and killings.
The extremists carry out spot checks, randomly entering homes, or stopping people on the street to check their phones and computers for transgressions.
If someone breaks the law, the justice system that shows no mercy.
Theft can result in lost fingers or limbs; blasphemy in death.
Hassan, the satellite-installation engineer, recalled how an acquaintance swore at a vegetable-stall owner who was selling him tomatoes at a price that he found too high. The acquaintance was immediately arrested. When during a prison interrogation he swore at the ISIS jailer and then at God he sealed his fate.
"They beheaded him in the main square," Hassan said. "They left his corpse there, with a sign saying 'Kaffir' [irreligious] on it. He was 20 years old."
And yet this autocracy remains better than the alternative, of living among the ruins of cities, such as Aleppo, destroyed by fighting on the ground and attacks from the air.
Even as the US-led coalition bombs jihadi targets (with airstrikes that are considerably more precise than those of the regime), the number of people living in their areas is said to be growing.
Population estimates vary, but aid agencies believe ISIS may have as many as 2 million subjects in Syria alone.
A resident of Al-Bab, an ISIS-held territory whose market last month was decimated by a regime barrel bomb, killing up to 50 people, said: "Civilians would rather live under monkeys than under Bashar al-Assad.
"They would choose anything than a regime that has been bombings its own people. Under ISIL we can exist, but still, we live in fear."
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