I've noticed that a few of the calling features have actually been released without any announcement. Two of them that I've noticed in the past couple weeks is presence sync between Teams and SfB, and Call Queues now also ring Teams clients.
Soooo... it looks like the roadmap was updated on 7/23/2018... and it has 3rd party SIP phones as a launched feature... Now I gotta ask where are the details? What phones are supported? Polycom does not have support listed yet nor have they released a new build. Anyone see anything from their phone providers yet?