That sounds pretty standard: normal questions can be a chat message; when it's useful to have an answer soon then SMS or call, or check if they see the message

That sounds pretty standard: normal questions can be a chat message; when it's useful to have an answer soon then SMS or call, or check if they see the message within a minute depending on your urgency. If it's an emergency and the call got pushed away or went unanswered, of course I'll just keep calling. Pretty common sense methinks