If you’re single, you’re likely no stranger to the 21st-century horrors of online dating. From the anxieties of messaging a stranger to failed first dates to ghosting galore, it can be enough to make you want to throw your phone out a window. While many of us may see romance via phone as a necessary evil, for single club-goers in 20th-century Berlin, it was the sexy alternative to saying hello IRL.

Rather than just walk up to the hot stranger on the dance floor, German nightclub guests too timid to approach a potential suitor face-to-face were welcome to flirt with fellow patrons using tabletop telephones or pneumatic tubes installed by the club. The practice was pioneered by popular Weimar-era nightclubs The Resi and The Femina. Each table at the clubs came equipped with its own telephone and a lit-up number placed where admirers could see it. All prospective suitors had to do was remember the number, pick up a telephone, and relay their amorous messages.

But as most online daters know, messaging complete strangers can be nerve-wracking. For those too anxious to contact their love interests directly, pneumatic tubes offered the chance to make messages anonymous. To go this route, patrons could write a message on a slip of paper, pop it in the tube built into each table’s handrail, and designate which table they wanted their note to be delivered to. To keep things respectful, every message was intercepted and either approved or denied by female employees in the club’s switchboard room before arriving at its final destination. In addition to handwritten notes, club-goers were also able to purchase a variety of gifts for delivery, including perfume bottles, cigar cutters, and Champagne.

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While The Resi and The Femina closed their doors in the 1970s, the telephone and pneumatic tube system has been memorialized in media. The classic 1966 musical “Cabaret” pays homage to the World War II-era method of flirting in “The Telephone Song” with lyrics like “Table five is calling number three, how are you?” Iconic novelist Ian McEwan also references the practice in his novel “The Innocent” when its protagonist visits a fictionalized The Resi and finds an advertisement for a “Modern Table-Phone-System” that “every night [sends] thousands of letters or little presents from one visitor to another.”

Most establishments have long done away with the pneumatic tube and telephone apparati. But clubs like the Ballhaus Berlin, one of the last remaining ball houses from the 20th century, still utilize a numbered phone system for patrons to use — a delightful reprieve from swiping left and right.