Step 1: Cancel the meeting.

could've been an email anyways.

@thebiochemic or even better a message in a group slack channel

@topsecret230 so many times I explain everything on Slack, manager doesn't understand, I say same thing in call, manager suddenly understands

@pandasama probably hes a visual person or extravert. I used to work with an engineer who was incapable of reading messages or writing messages. But face to face he communicated very efficiently. I remember him tellling me that he needs to see emotions on face and hear tone of voice then he can understand fully

I've had some succes with the Six Thinking Hats method, once everyone gets over the silly hat metaphor it worked quite well.
Provided you have people who can flow with the current hat colour.