So I setup NBN for my mum, who's over 80 and has numerous conditions. Also doesn't know how to use a mobile phone unfortunately. Moved from one provider to another. Tech came out today and couldn't connect it, and left without restoring service.
Upshot is that my mum now doesn't even have a phone at all. Old ISP says it's out of their hands, and new ISP says it's going to take at least a week to sort out. I know for most people this isn't as much of an issue, you can use 4g etc. but for the non-tech savvy, how can we have a system that allows the elderly to be without service for unspecified amounts of time?
Well the best method is as you mentioned, 4G. It can be up and running almost as soon as the device arrives. For example Optus provides 4G plans with WiFi modem. If you're looking for short term solutions there's also Prepaid 4G WiFi modems which you could leave plugged into a USB charger in the wall. Low fuss setup.