Rule reminder
In extended contexts, the correct periphrasis depends on: the temporal aspect (start, ongoing, end, imminent), the register (formal/informal), and the narrative relationship between events. Pay attention to time words (improvvisamente, gradualmente, sempre, da anni, stava per, appena) which signal which periphrasis is needed.
'Era una serata tranquilla. Marco leggeva quando, improvvisamente, il telefono ___.' (rang suddenly — action starts unexpectedly)