Medellín is 1 hour ahead of Dallas
Best overlap: 8:00 AM to 5:00 PM in Dallas is 9:00 AM to 6:00 PM in Medellín.
For the smoothest call, aim inside 8:00 AM to 5:00 PM in Dallas, i.e. 9:00 AM to 6:00 PM in Medellín. The overlap is wide at 9 hours, so you can protect mornings for deep work and still find plenty of meeting time. Note that Dallas follows daylight saving while Medellín stays put, so the times above drift by an hour seasonally.