This reminds me of when my workplace transitioned to a VOIP phone network.It took over two days to get our power restored and 6 days to get power to the local 'mast' . If it hadn't been for the BT copper system and us having an "un-smart" land-line phone there was no way to call for help in the event of a 'real' emergency. BT have stated they want to kill off the copper land-line system and replace it with a fibre based system. Similarly this and no doubt the next series of governments also want to kill off gas central heating and solid fuel (including firewood) fires. Soon everything will depend upon a supply of electrical power; and that seems to be getting based around wind. During the recent storm (even though we hadn't any power) we could see the local wind farm shutdown due to excessive wind. The following day it was again shutdown due to there being no wind. At one time the 'generating board' ensured there was capacity and resilience in the generation and distribution system, but such resilience is gradually being lost. My advice - make sure you have a good supply of candles and brandy.
Someone hadn't considered the need for emergency calls should the power go. Hence some very quick rewriting of risk assessments and nominating certain phones to be emergency phones; patched to specific UPS backed up switches in the LAN rooms!