My thesis on this is that instead of having a private company build and own the telecom networks (and have a monopoly in many regions), and then customers pay for it, we could save money as a community by just building it ourselves, like we once used to, and selling the services at cost (or less than cost depending what the infrastructure is, like roads or trains)

I remain pretty sceptical that privatisation has ever been a net good for the community, ever.

I'm not an expert in the modern comms protocols but I gather that ability was lost when the mobile protocols became packet-switched data-only protocols.

3G and below were "circuit switched" and internally made temporary "circuit" connections for calls. With the dedicated part of the protocol for making voice calls, any calls to 000 could be identified directly on the network and routed by them regardless of subscriber. LTE and later protocols only deliver data as IP packets, and no other special payloads, and do not keep track of connection/circuit state. On 4G+ voice "calls" are Voice over IP, sent as data packets on the network and treated the same as other data packets.

For the 4G or later networks to handle 000 calls especially, it has to let everyone connect to allow a locked down type of data roaming, and allow that roaming to only connect to the Voice over IP for 000. Which is entirely technically feasible, just requires more effort from the networks.

It is supposed to. Telstra engineer(s) were very surprised that it didn’t during their recent outage.

Some system failures are so severe that even failovers fail.

I have a dual sim phone which I use as my personal phone on one network and then work phone on another network so usually one works at any given time.