"If someone wants to have a synchronous conversation, I want them to state that."

The people that I would send a "you there?" message understand that my message is shorthand for that. They might respond with "in a meeting" or "gimme a few minutes" or if they are available for a synchronous conversation, "hey" or "what's up?"

I have a couple contacts that are "on the spectrum" and I deal with them a little differently. They seem to need things spelled out a bit more explicitly. But those people tend to get left out of many discussions, and don't seem to do as well careerwise in the long term, because they don't really connect on a human level with people.