[vacri]

Technically speaking, a recorded verbal contract isn't simply spoken word - it is a matter of record. It's just that the record is an audio file instead of a piece of paper.

About 11 years ago I did a short stint as a customer support bloke for a telco here in Australia. Recorded verbal contracts were the new fashion, and made life easier for switching phone companies. But every 'verbal' recording started with boilerplate stating that this was a recorded conversation, and constituted a contract. The content was specific points, like in a paper document. It was not a casual conversation. Things may have changed here in the meantime, but that's the way it was then.

I also think that a unilateral audio recording wouldn't stand in a lot of places, given that it's illegal in some places to record a private conversation without informing the other party.