Can you tell if a phone call voice is AI? My mother got a "grandson in trouble" call

My mother, 74, got a call from someone who sounded exactly like my nephew, crying, saying he had been arrested abroad and needed money for a lawyer. She nearly went to the bank. Is there any way to detect these AI voices, and what should I set up so it does not happen again?

I am sorry she went through that; it is a very common scam now and the voices are good enough that "does it sound real" is no longer a useful test.

Detection: there are AI voice detector tools, but over a phone line, with a crying voice and a bad connection, they are not reliable enough to bet money on. Do not build your defence on them.

What actually works:

1. A family safe word. Pick something odd and agree it with everyone. Any "emergency" call has to say it. Scammers cannot know it.
2. Hang up and call back on the number you already have for that person. Always. A real emergency survives a two-minute delay.
3. Money rules that never change: no bank, police force, lawyer or embassy asks for gift cards, crypto, wire transfers to a stranger or cash in an envelope. That request alone is the proof.
4. Pressure is the tell. "Do not tell anyone", "right now", "do not hang up" are the script, every time.
5. Reduce the raw material. These voices are cloned from a few seconds of public video. Set social media videos of the grandchildren to friends-only.
6. Tell the bank. Many banks will add a note to call a second contact before large cash withdrawals for older customers.

Report the call to the police even if no money moved; the numbers matter for takedowns.

The safe word thing works. We did it after a similar call and my father now answers every unexpected "emergency" with "what is the word", which is both effective and very funny.