California is a two-party consent state[0], which means everyone on a phone call must agree to it being recorded before it can be recorded.

In general, many more US states are one-party consent[1], which means that only one member of the conversation has to agree to the recording.

[0]: https://en.wikipedia.org/wiki/Telephone_call_recording_laws#...

[1]: https://en.wikipedia.org/wiki/Telephone_call_recording_laws#...