I wonder if one could turn on that option on their old phone before switching numbers. Yes, one can, and this is the correct and documented way to avoid this p

I wonder if one could turn on that option on their old phone before switching numbers. Yes, one can, and this is the correct and documented way to avoid this problem. Unfortunately, people don't generally think about it before asking their carrier to swap out phones on their line, and your iPhone has no way of knowing you intend to deactivate it.