One way: Everyone has a code-word which they only share with humans, over "private" channels like direct voice calls. For example, I'm "pineapple", and you're "orange", when we're connected on a call, we share our code-words in order to "authenticate" the call.

Another way: have a passphrase with a group of people that you share with each other, that is hard to guess but memorable. "The sky was green this morning" for example, that everyone in your family knows is the "human passphrase".

Another way: ask personal questions only the actual human being would know, like inside jokes or specific details about their life.

Another way: verify through some out-of-band method (like text message) in order to confirm their identity.

Another way: start everything with a video call where they have to pass their hand in front of their face before switching to audio only

None of the methods are perfect, all come with pro and cons.

But writing all of this made me feel really dystopian for some reason...

Someone should make a family authentication app. It would generate a TOTP secret and associated QR code that could be shared with other family members. (This app does not have to be a mobile app. It could be a desktop app, or even a web app that runs locally in the browser).

Have every family member scan that code for use with the TOTP authenticator of their choice on their phone and/or tablet and/or watch.

When you are talking to someone who purports to be a family member you ask them for the family TOTP code and check to see if they give the same code that your TOTP authenticator on your phone or watch is showing.

Ask if Wolfie is ok.

Passwords. Think flash/thunder, but more casual.