Helsinki is 7 hours ahead of Medellín
Best overlap: 8:00 AM to 11:00 AM in Medellín is 3:00 PM to 6:00 PM in Helsinki.
For the smoothest call, aim inside 8:00 AM to 11:00 AM in Medellín, i.e. 3:00 PM to 6:00 PM in Helsinki. With 3 hours to play with, a mid-window meeting keeps things balanced for Medellín and Helsinki alike. Note that Helsinki follows daylight saving while Medellín stays put, so the times above drift by an hour seasonally.