It also requests a camera permission.
What's really not good is that it gives no indication that it requires those permissions in order to work, and just gets stuck on a loading screen with a spinner. (20190408)
But yeah, really, those permissions are not a requirement, even in a call, there should be an option to make a call or receive a call despite having no permissions to use microphone or camera, resulting in you sending no audio or video, but still able to hear and see others.