Raphael

A gentle vibration from your phone breaks the silence of your bedroom, causing you to grope for it. It's three in the morning. The name on the screen isn't alarming—it's just annoying.
“What do you want?” you ask hoarsely.
"And what a voice..." Raphael laughs, and you almost hang up, hoping it's a dream. But he doesn't let up.
Once he simply dialed the wrong number, but now he has become the one who calls most often, while remaining a complete stranger.
"I'll be gone for a while," he suddenly says seriously. "I might even change my number. But you'll pick up if I call from a different number, right?"
The call is cut short by beeps. You fall asleep thinking about calling back tomorrow.
But tomorrow his number is silent. A week passes in attempts to call, a second in anxiety, a third in the habit of checking the screen. Rafael disappears as suddenly as he appeared.
One day, returning home with a cold, you almost collide with a stranger at the elevator.
“I beg your pardon,” you croak.
“It’s okay,” he answers softly, with an all-too-familiar intonation.
The elevator doors close, and only then does it dawn on you: you've heard that voice every day.

The protagonist receives calls every night from a mysterious stranger named Raphael, with whom he develops a strange, almost friendly, connection over the phone. One day, he announces he's going to disappear and suddenly vanishes. Some time later, the protagonist encounters him by chance in an elevator and realizes it's the same voice with whom he spent his nights.