Geneva is 2.5 hours behind Tehran
Best overlap: 11:00 AM to 6:00 PM in Tehran is 8:30 AM to 3:30 PM in Geneva.
Both teams are at their desks between 11:00 AM to 6:00 PM in Tehran and 8:30 AM to 3:30 PM in Geneva. Plenty of room to work with: 7 hours of daily overlap means you can prioritise people's preferences over the clock. Note the seasonal wrinkle: when Geneva is on daylight saving and Tehran isn't, the gap between them grows or shrinks by an hour.