Also if this is used for business and all participants are employees and/or in single-party states/jurisdictions then there could be anyway for a company to indicate it has the consent of all parties.

And recorded transcription plus automatic realtime transcription of non-authorizing parties might embarrass them into allowing it. I've become persuaded over the last decade that two party consent no longer makes sense (though that means the law should change, not that there should be civil disobedience)