It almost certainly did not operate in any way similar to how it was described in the article. See my other comment but I highly suspect this was a much simpler

It almost certainly did not operate in any way similar to how it was described in the article. See my other comment but I highly suspect this was a much simpler solution in real life. I don't think there was any monitoring of "code words" at all or even any automated voice detection. It just seemed that way to outsiders because all they ever saw was the correlation without actually understanding the capabilities behind the scenes.