DTMF, short for dual-tone multi-frequency, is the signaling system behind touch-tone telephone keypads, developed by Bell Labs and introduced commercially in the early 1960s. Each button press sends a pair of tones that telephone exchanges decoded as a digit. Decades later, these familiar beeps became raw material for internet creators: the rise of vaporwave, lo-fi edits and analog horror gave old phone sounds a second life wrapped in VHS hiss and tracking errors. Clips like this one thrive on that nostalgia, turning an everyday dialing noise into a retro storytelling tool.