My phone shows a live transcription of the message being left.

If I see that it's an important call, then I can pick up and answer right there mid-voicemail.

That's what I was referring to. They start talking when they leave the voicemail.

This is how we did it for a long time with home answering machines too. Except instead of reading a live transcription, you listened to their live recording, and could interrupt it and answer if you wanted to talk to them. It's not a new idea.