I am also curious to see who thought this would be a good idea, and why Microsoft Teams (along with other contemporary Microsoft products) are difficult if not impossible to customize. Some users have reported that this function actually makes their work significantly less productive, presumably on Microsoft Windows using software by Microsoft.
Incidentally, Control + Shift + C is a shortcut used by other web browsers which are compatible with Microsoft Teams. For the tech savvy among us, these web browsers can be customized to accommodate Microsoft's constant need for more resources, more key bindings, and more of everything else that we did not want to give them, and I'm interested to see how this will play out. Conveniently, edge uses a nonstandard shortcut for the Inspector developer tool, so as to not interfere with Teams. Is it in Microsoft's nature to not play well with others, or is it just Teams? Maybe Edge support on third party browsers will be discontinued so that a marginal amount of Teams users can save 0.5 seconds by using a keyboard shortcut instead of clicking a button, while many more uninitiated users make accidental calls.
Taking into account human reaction time and the heavily laggy Teams platform, one might expect that these unintentional calls will result in many awkward conversations. Maybe that's what Microsoft or the Teams team wanted. Only one thing is certain, and that is we users do not expect a timely response or solution. This issue could drag on for years until Microsoft finally admits that having a keyboard shortcut for phone calls was a silly idea. Those of us who work at night will never need to use that feature, and may switch to Outlook instead of having to use Teams (if our organization made the unfortunate choice of using it).