Fair, I was not aware of that exception. It does seem to cover this case, assuming Google is actually not sending any data outside of the phone, use it for further training etc.

The person owning the phone where the processing takes place, is the processor of the data in this case. That still requires consent from the data subject per gdpr.

In many places call recording (or indeed processing of personal information which is highly likely to be present in phone calls) requires consent to be legal. I highly doubt this kind of processing is legal in the EU without both parties consenting.

If you are open to building something yourself this might be an alternative (disclaimer: I just know of this project but no idea how well it works): https://www.findmycat.io/