They are both types of chats. We use a combination of skype for business and zoom (zoom supports external people far better than skype, and actually works better in all regards).
Our time zone difference isn't as extreme as a 10 hour difference. We have offices -1 and +1 from our current time zone so it makes it easier.
A talk I attended earlier this year had a similar setup to yours and what they did was record all meetings and had a culture of always doing the meeting regardless of wether people could join. Then if you missed the time you chimed in later after you watched the video. Decisions were handled in a similar async fashion.
Our time zone difference isn't as extreme as a 10 hour difference. We have offices -1 and +1 from our current time zone so it makes it easier.
A talk I attended earlier this year had a similar setup to yours and what they did was record all meetings and had a culture of always doing the meeting regardless of wether people could join. Then if you missed the time you chimed in later after you watched the video. Decisions were handled in a similar async fashion.