I know there are a couple of threads on this topic, but they all appear to have been closed, so I can't add this new info to them.
Sometime in the last couple of weeks, https://support.office.com/en-us/article/control-calls-using-a-headset-in-teams-65d6e104-444d-4013-b... has been updated. The notes on the CX300 now say "The Polycom CX300 supports basic call controls such as answering, ending, and muting phone calls. Support for the phone's dial pad and display is expected in a future update."
I tested just now in Teams version 1.3.00.362 (64 bit) and was able to answer an incoming call just by lifting the handset. This is different to about two weeks ago when the hookswitch was completely ignored. This works even when the CX300 is not my default audio device in Teams.
Hanging up the handset does not end the call, it instead transfers it to the CX300's speaker. The mute button does now work. I also tested with the Plantronics 540-M and got the same results.
So, there's some progress! Someone at Microsoft is working on this. Hold on to your hope people
Hello @Wim Allegaert ,
We cannot discuss future software Versions or hardware within the Community.
Poly, a US-based company, cannot share any future release dates or new features due to the requirement of non disclosure agreement / NDA prior to this.
Via the medium of a community forum, we are unable to do this.