error message facetime audio failed - both devices up-to-date, no blocks, checked and reset. however, the audio 'tab' in facetime when opened is not present, as if it were somehow removed.
Welcome to the Apple Support Communities! I understand that you are experiencing some issues with FaceTime calls on your iPhone 5. It also sounds like you have already tried troubleshooting these issues - good job! I wanted to provide you with the following resource in case there were any steps you have not attempted yet: