Thanks for that John although Microsoft support is giving a different message - I raised a support ticket and they started talking about putting the switch to Teams on hold for a month but that after that, our Yealink phones won't work at all. This is at odds with what's been said here. We're actually using common area phones shared between two people and these only went in four months ago. I tried to get them to shift to softphones on their mobiles, but met with resistance. However, I managed to get a small team in a new office to go softphone only using USB headsets and mobiles - they are quite happy.
It is totally unacceptable for SfB hard phones to stop working when the tenant is switched to Teams. Not only is that very recent investment wasted, I'm going to look very foolish for recommending them. Never if my wildest dreams did I expect new hardware to be useless in <6 months. So I really do hope you're right John and that our common area phones will continue to work as plain old phones - you know, receive a call and make a call. My client isn't currently using any of the other features so they won't be missed.
I appreciate that the new Teams client is built on Android (we have three CP960s as well) and now understanding that, I accept that the phones can't be upgraded to support Teams but those old SfB hard phones must keep working for at least a couple more years.
There is a lot of frustration and pain on this thread - I do hope Microsoft is listening. They are not beyond brave reversal of intention - see how they abandoned the Edge rendering engine.
Regards, Rob.