ChrisWebbTech just chiming in, like wimvanhouts said, even the "new" api's are extremely lacking. To be honest this is my single biggest frustration with teams, if not Microsoft as a whole.
We are a full stack MS customer with Dynamics 365, PBI, AAD, etc, and just simply trying to get integrations to work with Teams so we can have basic functionality that existed for a decade in SfB/Lync is still basically impossible even with the new API's. It seems like developers for these API's aren't listening to any user input and simply released something just to say that an API actually exists now.
I'm not trying to be ugly by saying this but from our end it seems like MS cares more about walkie talkies and praising people in teams than they do making their voice truly enterprise. The level of progress for a functional API is honestly unacceptable. At the very least MS needs to have disclaimers for their Teams Voice to prevent orgs from falling into a trap with a voice solution that can basically not be integrated with anything, much like our org fell into over a year ago.