[question] How to fix iPhone no longer allowing audio/video interaction on calls/FaceTime?

My wife’s iPhone (7, iOS 12.1.1) just stopped allowing audio or video for calls. We were on the phone and suddenly I could no longer hear her. She tried FaceTime and it still acts like it is calling and connecting but n9 video or audio. Regular calls will connect but no sound sent or received. Speakers work, camera works. iMessages stopped working but after signing out, restarting, and signing back in it works again. Just hoping there is a common bug that I can easily fix. Thanks for any help.