The problem with moving phones from copper to fiber: power

If you can’t contact your loved ones, or government agencies and relief organizations can’t coordinate, you can’t get anything done. […] A communications system is only useful if you can connect to every other endpoint on the network. If you have power but no one else does, you have a well powered and expensive paperweight (assuming you still have paper). To that point, if your phone has power but the switching station does not, or the cell towers in half the city are down, you still aren’t able to communicate with anyone else.”

emtcharlie on ArsTechnica