Does the time difference between Cairo and Dubai change during the year?

Yes. Because of daylight saving time the gap moves between −2h and −1h.

When is the best time to call Dubai from Cairo?

Between 09:00 and 16:00 in Cairo, which is 10:00 to 17:00 in Dubai.

Cairo is 1h behind Dubai. This gap is not fixed: daylight saving time moves it between −2h and −1h during the year.

Cairo

Egypt

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Dubai

United Arab Emirates

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A 9-to-5 day in each city overlaps for 7h. That is 09:00–16:00 in Cairo, which is 10:00–17:00 in Dubai.

City	Time zone	UTC offset
Cairo · Egypt	Africa/Cairo	UTC+3
Dubai · United Arab Emirates	Asia/Dubai	UTC+4

What is the time difference between Cairo and Dubai?: Cairo is 1h behind Dubai. This gap is not fixed: daylight saving time moves it between −2h and −1h during the year.
Does the time difference between Cairo and Dubai change during the year?: Yes. Because of daylight saving time the gap moves between −2h and −1h.
When is the best time to call Dubai from Cairo?: Between 09:00 and 16:00 in Cairo, which is 10:00 to 17:00 in Dubai.