Skype for Business has been my Mac's default phone call app ever since I installed it. Is there a way to switch to FaceTime—or better yet, handoff to iPhone?
When I place calls from my iPhone, I can switch the audio to my Mac.
Open FaceTime on your Mac, select FaceTime > Preferences, select Settings, then change Default for calls to FaceTime.
Contacts.app
's "FaceTime Audio" option, but for the "Call Using iPhone" one as well.