I have a support ticket open on this but wanted to see whether anyone in the community saw this behavior.
On Windows 11, Sangoma Phone with a USB mic is forgetting permissions given to it for the mic after a few hours of use, and then popping up a notice “Cannot join the call. The app does not have permission to use your microphone.”
No issue on MacOS or Windows 10. It seems to be a Windows 11-specific problem.