What causes continuous ringing on iPhone FaceTime calls?

Recently I was on an Alaska Air flight and connected to the WiFi. I had a FaceTime audio call going and it failed, when I tried to call back it rang continuously and it only stopped when I hung it up. This also happened when I called on instagram audio. I have a 15 pro max. I do need to update my software, and my storage is nearly full. I’m unsure if those factors matter. Also the person I was trying to call has no record of my attempted phone calls, they only appear on my log.

Has any one else experienced something like this? And what could be causing it?

[Re-Titled by Moderator]