Call controls need to remain visible when doing other Teams activities
We use Teams with Microsoft phone system, aka cloud voice, and make and receive PSTN calls frequently from Teams.
If you place an outbound call and then, during the call, navigate to a channel to open a document, Teams desktop will often hide the call controls. When this happens, the only way to see call controls seems to be to close the document - which, of course, defeats the purpose of viewing a document while also managing the active call.
Steve Whitcher commented
Ideally, we should also be able to access these without having to have the full teams app up on screen. I'd like to see small pop up window with the call status and controls, which appears when Teams is minimized while on an active call. This would be similar to the behavior of Skype for Business.