Why don't you do the same? Show you aren't someone to be stifled with?
Like say, hey, these are my working hours in whatever his local timezone time. I am most effective in this time. Let me know what works for you within this timeline so that we can effectively communicate and move things forward.
Remember, unless you take stand for yourself, no one else would. World is a selfish place to live in, and standing up for yourself is one of the most effective lessons you can learn.
If the person still suggests rescheduling, ask them to give a time within the slots you are free in. Before the call, 1/2 hour before, Just check in, if they would be joining