Not all too long ago I had someone port out my VOIP number. They had it for a few hours. This was after I had spent extensive effort attempting to secure my digital life. VOIP was SIM-swap resistant sure, but I totally missed that port out requests default to failing open.
Thankfully the VOIP operator alerted me and pulled the number back. Then I set a port out code.
Who knows how many other holes I have. I lost my sense of smugness that day.