And more to the point, if it makes logical sense, the govt. would never have done it.

That is a given in 99% of cases. The last 1%, they just don't do it and not give any reason.

Now the former monopolies still have those buildings, and now plenty of space inside as electro-mechanical gear (Strowger, Panel-switch, Crossbar) used wide rack frames: Seems the new wonder gear is oriented for the standard 19-inch type racks. Ironic as the 19-inch "Relay-Rack" may predate telecom-tech, originating with the Railways!

Where I work, we purchased a new PABX a couple of years ago. It is in a 48 unit 19 inch rack, along with the battery packs, UPS, voicemail server, etc. I was surprised that this stuff is still available with the advent of VOIP happening a long, long time ago, but apparently, standard PABXs are still quite a popular purchase, especially in larger installations where it is cumbersome to wander around swapping hundreds, or in our case around 1,500 extensions over.

The rack cabinets are a lot tidier. The previous PABX was in self-contained magazines with missing panels and redundant wiring hanging off it like C3PO.

I'm suprised your work splashed out on a PBX that has that much physical kit, unless if you're not cabled up for VoIP. Typically you'd throw a couple of call servers in (3 or 4 for redundancy) which are 1-2U servers, and some other voice gateways required for VoIP <> Analogue if you're still using fax machines. These are typicaly 1U for 24 lines.

Then again, some players like Avaya still like lots of cabinets with specialty hardware, rather than implementing it in software. I remember doing an audit of an upgrade to a bank's central PABX for their call centres. Around 3000 extensions. It was a total of 20-odd 48U racks of kit across AU and India, and was all brand new!

There is cabling for VOIP - the existing computer network would have supported it - but as I said, the changeover would have been too disruptive. Whilst there is much checking and programming to do when installing a PABX, the actual changeover time is only a few minutes as both PABXs are double-jumpered to the MDF during the transition. It was a simple matter of unplugging the old jumpers and plugging in the new ones. Once the new machine was proven to be up and stable, the old cabling was simply torn off the MDF and the job was done. The new machine is a Mitel MX1, which is basically Ericsson gear.

There's about 40 fax machines in the place, in addition to EFTPOS and HICAPS machines, alarm monitoring, public phones, etc. If the building was just being built now - yep, VOIP would have been a better solution.

Yeah that makes sense then; there are definitely cases where it would be a pain to upgrade, and therefore you still have to re-use the old TDM handsets.
The good thing with the MiTel is that it's a hybrid system so now the platform would be in a position to be migrated extension by extension from TDM to VoIP handsets, thereby future-proofing the installation.

The MX1 is upgradable, yep. The good thing about it is that the VOIP handsets look exactly the same as the current ones and also work and sound the same, so people won't need to learn to drive again, so to say. In fact, if no-one was told an upgrade was happening, I doubt they'd even know anything happened aside from wondering why they were being given another phone.

"..keep the proper telephone network alive so that people can ring 000 in emergencies and still be able to use their phones when the lights go out.."

I noticed the early roll-outs of phone-over-modem - from both Telco & Cable - had companion Ni-Cad packs for power out emergencies.

-- Were they just being nice, or were they compelled by law to offer power backup? --

They soon quit doing this (as more people gained 2nd Mobile service?) Or are they gambling with the low risk (emergency + no power + no mobile) finding it cheaper to pay rare lawsuits with insurance?

On fibre, you can get the option of a small UPS that is built into the CPE gear but I don't think this is offered for users that stay on copper connections. As far as I can tell, few of the fibre customers opted for the UPS because of the extra cost. Those who 'inherit' this gear by way of house sales, etc, are likely to end up with a modem that has a dud battery anyway.

"option of a small UPS"

I had the option at extra cost of a small UPS but declined because it gave (from memory) 30mins of supply then turned its self off; then a further 10mins available after that.

Decided this was pretty useless having three mobile in the house and no relevant medical issues.

But if did decide as we get older/ill that an emergency contact facility was appropriate, am I legally able to provide and install my own, bigger capacity UPS for the NBN gear and a phone to plug into?

Yes absolutely. It's a standard GPO.

In fact, it's recommended by providers if you want continuous voice and/or internet service. 95% of retail providers will only deliver a phone line over VoIP to their supplied router, and very rarely will they provision the UNI-V ports for voice. As such, you'd need to keep your router alive as well if you want phone.

I am in the process of converting the one up at the farm to be completely 12V DC operated, off grid (due to the tendency for the power to kill electronics up there), and removing the UPS that we use.

OK, thanks for that. Should consider moving to VOIP.

Operating on 12V would be the same as alarm systems so that should be easy to manage.

I dont think the 12V move is sanctioned though Just using their supplied plug pack on a UPS.

Jaycar sell the plug used on the FTTP and Fixed Wireless NTD's, however it's just 12V presented on 2 of the 8 pins.
The FTTC uses a plug pack in the order of 48-60V, due to it powering the DPU in the street.
HFC has a standard 12V plugpack with the barrel style connector.
FTTN/FTTB uses the retailer supplied modem, there's no equipment provided by NBN. So whatever the modem takes is what it uses.

As for Skymuster satellite, I'm not sure, but from my understanding it'll need to power the LNB and the transmitter, which I would assume needs a larger power supply, I think they are putting out signal at around 20W, but I'm happy to be corrected on that one. Therefore the PSU would need to have a bit of grunt behind it.

Edit: Jaycar PP2028 is the connector for FTTP and Fixed Wireless
https://www.jaycar.com.au/300mm-nbn-ufb-power-connection-lead/p/PP2028