How to conference call with FaceTime audio?

Solution 1:

It's not possible to have group call with Facetime Audio at this time. Apple used to have this feature in iChat but removed it because it was a poor experience.

There are other third-party apps that have this type of feature and those might fit your needs.

EDIT: Adding additional info from the discussion in comments.

The date of that article was June 2014 and was talking about pre-release iOS 8 (which came out in Sept 2014). Maybe it was available in the beta, I don't know. Like you, the articles I read all came out around the same time and it looks like they're all using the same wording leading me to believe they're all using the same source. I could be wrong but I can't find anything on Apple's product or support pages indicating how to do this.