The Pomodoro Technique is a time management method developed by Francesco Cirillo in the late 1980s. It uses a kitchen timer to break work into intervals, typically 25 minutes in length, separated by short breaks. Each interval is known as a pomodoro, from the Italian word for tomato, after the tomato-shaped kitchen timer Cirillo used as a university student.
It’s possible that I was just doing it entirely wrong, but I seem to recall (from when I tried it years ago) that I would still get interruptions (like phone calls, meetings, and slack messages) but then the timer would go off during those interruptions.