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?
Well technically SIP phones can now take and receive calls when Teams is setup as your only platform. Even thou the firmware itself isn't connecting to Teams with the whole unified presence etc. That might be what they mean by that item, not necessarily that all your 3rd party phones will have direct updated firmware, but they will interop now with Teams calling, which in fact does work, at least for my phones here in my office :P.