There is no time difference between Frankfurt and Paris. Both cities use Central European Time (CET, UTC+1 in winter and CEST, UTC+2 in summer). When it's 9:00 AM in Frankfurt, it's also 9:00 AM in Paris.
Both cities observe daylight saving time on the same schedule, so they remain synchronized year-round.
Any time works! Since both cities share the same timezone, you can schedule calls during standard business hours (9:00 AM - 5:00 PM) without any time conversion needed.
Frankfurt and Paris are major European financial centers, connected by high-speed trains in about 4 hours or by plane in about 1 hour. Frankfurt hosts the European Central Bank while Paris is France's business capital.