I've experienced some issues while using the teams mac app. Sometimes when I called someone, the ringtine hasn't stopped ringing after joining the call.
After some time I've been finally able to reproduce this behavior and find the bug that causes this issue:
When you receive a call or call someone, the Team Client (at least the mac one) plays an audio file using some kind of background audio player. So when I accept the call, the ringing stops (audio player stops "ringing" playback). When I was listening music just before the call and try to stop the music (in my case spotify client) using the play/pause key on by keyboard, spotify is no longer responding to the play/pause action but instead the hidden "ringing" player from teams. Therefore I just start/stop the "ringing" sound from teams using the play/pause key on my keyboard.
I guess this ain't a feature, so I thought I give you guys a quick feedback about this bug.