[Standards] Voice Notes

Hi All, At the online summit there was some discussion about voice notes, which I hate. But, they've come up on a requirements doc I'm working to, so I thought I might see what the current best-practice / specs are. Do we have any? Are we using SIMS, SFS, OOB, or just putting a URL in the body and hoping everyone knows what we mean? Or all of the above? Dave.