If they do the same thing, now it takes potentiality days of "phone tag" before you happen to find a time you're both free. With async comms, you initially go

If they do the same thing, now it takes potentiality days of "phone tag" before you happen to find a time you're both free. With async comms, you initially go back and forth over text/chat/email/whatever. Sometimes resolving in minutes/hours. If you both decide it'd be faster to chat synchronously, you schedule a call and do that. Honestly, that fact async comms exist makes it kind of presumptuous to assume you can make someones device ring at anytime and just get their immediate and full attention. I feel that way both as a caller and callee. There's obviously exceptions, such as immediate family: but we roughly know what each other are doing, and the context. If my wife actually phones me, I will drop whatever I'm doing because it's guaranteed to be more important.