facetime
If i get an facetime call from someone and i try to answer it, it joins the call but immediately dumps me out of the call.
Question marked as
FaceTime requires a broadband or cellular connection with sufficient bandwidth.
Restart your iPhone, and try again.
Failing that, update your iPhone to iOS 15.1 and try again.
If there’s an add-on VPN client app around, remove that and try again.
If you can't make a FaceTime call on your iPhone, iPad, or iPod touch - Apple Support