Does the time difference between Jakarta and Melbourne change during the year?

Yes. Because of daylight saving time the gap moves between −4h and −3h.

When is the best time to call Melbourne from Jakarta?

Between 09:00 and 14:00 in Jakarta, which is 12:00 to 17:00 in Melbourne.

Jakarta is 3h behind Melbourne. This gap is not fixed: daylight saving time moves it between −4h and −3h during the year.

Jakarta

Indonesia

--:--:--

Melbourne

Australia

--:--:--

A 9-to-5 day in each city overlaps for 5h. That is 09:00–14:00 in Jakarta, which is 12:00–17:00 in Melbourne.

City	Time zone	UTC offset
Jakarta · Indonesia	Asia/Jakarta	UTC+7
Melbourne · Australia	Australia/Melbourne	UTC+10

What is the time difference between Jakarta and Melbourne?: Jakarta is 3h behind Melbourne. This gap is not fixed: daylight saving time moves it between −4h and −3h during the year.
Does the time difference between Jakarta and Melbourne change during the year?: Yes. Because of daylight saving time the gap moves between −4h and −3h.
When is the best time to call Melbourne from Jakarta?: Between 09:00 and 14:00 in Jakarta, which is 12:00 to 17:00 in Melbourne.