When the Phone Rings: Plot, Cast, Ending & Where to Watch

Yoo Yeon-seok

Yoo, eleven years after his breakout in Reply 1994 and well into the leading-man phase that ran through Hospital Playlist and Hometown Cha-Cha-Cha, takes the rare role of the controlled, dangerous male romantic lead. Sa-eon is a spokesperson whose career runs on language and whose marriage runs on its absence, and Yoo plays the contradiction without leaning on the warm-eyed register Korean audiences expect from him. The performance is one of his coldest, and it is the engine of the show's premiere-month viral momentum.

Chae Soo-bin

Chae, who anchored Strongest Deliveryman and I'm Not a Robot, takes the role that quietly carries the series: a sign-language interpreter who has chosen not to speak inside her own marriage and whose silence the show treats as authored rather than inflicted. The performance requires Chae to do most of her acting with her face and her hands, and the choice to break the silence becomes the series's tonal hinge. The role won her significant attention at the 2024 MBC Drama Awards.

Heo Nam-jun

Heo, a steady second-male-lead presence in My Demon and Bloody Heart, plays the investigator with the procedural calm the show needs to ballast its melodrama. Sang-woo's relationship to Hee-ju is one of the series's longer-running secondary threads, and Heo plays the investigator's investment in the case without telegraphing whether it is professional or personal until the script earns the reveal.

Jang Gyu-ri

Jang, an idol-turned-actor after Fromis 9, takes the reporter role with the kind of focused, slightly abrasive professionalism the show needs to break up its long marital-silence stretches. Yu-ri is the outside voice asking the questions the audience wants asked, and Jang plays her without softening the ambition that makes the character useful to the plot.

Lee Doo-seok

Lee plays one of the series's quieter supporting figures, a character whose function in the household pivots between household staff and household witness across the season. The performance is held back deliberately so that the late-season reveals can land, and Lee's stillness across the first six episodes is one of the show's better small-scale acting choices.