"You didn't have to give them any personal details about yourself. You didn't meet them face to face. It seemed like a safe, easy way to make money quickly. I set up an anonymous Instagram account and soon had guys messaging me."
Moving off Instagram to make sure she was even less traceable, Katie began to find work on online forums filled with men offering large sums of money in exchange for a 20-minute text conversation.
"Whenever I see anyone post a 'wanted' ad asking for something I'd be fine with, I send them a personal message," she explains, adding that she prefers to answer ads directly rather than advertise herself.
On their ads, "people describe their budget, their kinks, if they are looking for anything specific. It gives me a chance to veto them before them seeing a picture of me".
Her clientele is mostly American, and prices vary depending on the whether their communication is just verbal, or involves pictures and videos.
Now, Katie - whose boyfriend is supportive of her digital sex work - is extending her services to include Girlfriend Experience or GFE, where men pay a woman they find on the internet to pretend to be their "girlfriend", by way of exchanging regular texts.
"It's kind of sad," she says, but "one guy in America paid me US$250 (NZ$380) a week, and it was just occasional texting."
Doing this every week earns Katie more than most students slogging their guts out on zero-hour contracts in high street shops. And she is by no means alone: a recent study by Swansea University found that 5 per cent of students had done sex work at some stage, while 20 per cent had seriously considered doing so to pay their bills.
Brighton University launched an investigation this week after a sex workers' support group ran a stall offering help for students at its freshers' fair.
The decision to allow the Sex Workers' Outreach Project Sussex (Swop) to attend events in the city and on the Brighton and Sussex campuses was slammed as "beyond disgraceful", with many slating the stall as little more than an inappropriate endorsement of sex work.
Among students, attitudes are very different - no wonder, perhaps, at a time when hefty tuition fees and rising rents mean multiple jobs alongside their studies are required to make ends meet.
A few hours spent talking to students in bars and cafés in Brighton and London this week were more than enough to convince me of the casual ubiquity of student sex work.
In fact, there wasn't one person I spoke to who, when asked if they knew anyone who supported themselves through university in this way, didn't reply with some variation on: "Oh yes. My housemate does a bit of 'camming' when she needs the cash, and a couple of friends are signed up to a sexting app or send pictures of their feet to guys on Snapchat."
If the image you had was of students soliciting clients between lectures, or getting dressed up every evening to work as high-class escorts, cast it aside: face-to-face communication of every kind is diminishing, and that extends to sex work, too.
For years, we've heard about students "sugar-daddying" to pay their way through university, courting rich older types who are in need of companionship and have money to burn.
It's still a vastly popular choice - Seeking Arrangement saw hundreds more subscriptions this year, including 950 students from the University of Kent alone.
In a bustling Brighton bar, 24-year-old Natalie, a second-year computer sciences student "living on a shoestring budget", tells me that she has used sexting to supplement her student loan for the past two years, and is about to start doing some webcam work.
For her, this is a no-brainer.
"I don't have the time to get a well-paid job and study," she says.
"This way I can go to uni all day and then come home and get naked on a camera for a couple of hours then go out with my friends and have a bit of a social life.
"I think people are under the impression that if you want to do sex work, it's because you want to get loads of cash to buy expensive shoes or something - but it's not that at all. Lots of students need a bit of extra cash just to live."
And webcamming can be lucrative, earning some up to £1000 (NZ$2000) a week. Natalie currently makes up to £200 (NZ$400) in a week from messaging, though adds that many of her friends earn £50 (NZ$100) a week "doing not much at all" - sometimes merely corresponding with men about "their jobs and how stressed they are".
A couple of her friends sell pictures of their feet to fetishists on Twitter for upwards of £5 (NZ$10) a pop, while the site is also replete with practitioners of "findom", or financial domination - people who pay others to take control of their passwords and online bank accounts, which is, apparently, arousing.
Amazon gift cards are also a popular payment method in lieu of hard cash, as are websites that allow you to create your own gift list for clients to purchase goods on your behalf.
Like many digital sex workers, Natalie uses a pseudonymous PayPal account to avoid handing over her details to strangers and, "because if PayPal find out you're using it for sex work, they'll block you. But a lot of websites skim the top off your earnings, so it's better to do it independently."
To many, the idea of soliciting sex work over the internet might seem like a last resort option, the path you would only ever turn to if utterly desperate.
Yet those I met all shared a total absence of shame around the topic, chatting as openly with friends about camming as they would a Saturday job in Boots.
Organisations such as Swop have been lambasted for endorsing student sex work, but for the students I spoke to, receiving a leaflet at a freshers' fair would never have been the catalyst for their taking it up.
"I've never met anyone who would choose to do this just because someone at a freshers' fair handed them a condom," explains one student.
In many ways, of course, sex work is a last resort - but it isn't happening in the shadows, or on the dark web.
It's happening every day, in student halls up and down the country. And the 5 per cent of students who do it see it as little more than a necessary, safe way to make a bit of extra cash.
Does it ever feel demeaning, I ask them, to do this kind of work?
The unanimous reply is no.
"I've never felt uncomfortable," says Natalie. "It's good for just getting that little bit of extra cash. If anything, it's empowering to earn your own money and use your body in a way you're in control of."
*All names have been changed
