It’s true that network and IT resilience is no where near what was considered normal, although availability of telephony service has improved. Mind ewe, that has more to do with a change of usage pattern than anything else because we no longer have busy hour or of peak. QoS used to be targeted at 90% successful call connections of busy hour traffic.
Telephone exchanges all had batteries and standby generators, but the destaffing of exchanges buildings resulted in no routine maintenance of the generators and thus many of the engines failing when someone eventually decided that testing them was a good idea. Initially, battery capacity was spec’d at 24 hours, but that soon dropped to 1hr in city centres. The battries also provided final power smoothing, something else that became less used as digital exchanges had power units on each rack.
