Do you remember when the fax machine ended?
No?
No, neither do I.
I remember having to scrabble around with a PC that still had a modem in it back in around 2011 to send a fax as part of a mortgage application.
I remember around the same time receiving someone else’s details in a fax from my bank, a misdemeanour today which would end up with a trip to the ICO naughty step.
I remember in the mid-2010s working with a law firm where they still had a networked fax server infrastructure that instigated a category 1 response if it failed, but was barely used.
Fax was around forever (the earliest incarnations of the printing telegraph were invented in the 1840s), but whimpered out. It was there and then we didn’t really notice that it was gone.
Popular storytelling about the emergence or disappearance of technologies tends to be very binary. Big appearances, sudden exits. But the reality is of long noses and long tails.
I vividly remember a conversation with my father in the mid-1980s about how pointless the fax seemed when you could email things. Those servers would still be sitting in that law firm three decades later. Technology slowly emerges, and its rapid acceleration in an exponential curve fools us into thinking it happens suddenly. The same happens in reverse.
And so it is with the telephone. When did you last use a phone?
We got rid of our landline telephone at home a couple of years ago. Occasionally I’ll phone someone, but the reception in our house, patchy because of various steel beams, usually makes it easier to WhatsApp or Teams. I’ll tend towards online services over waiting in a queue being told that my call is important, but not quite important enough to have enough people ready to answer it.
When I started working at Reuters in 2005 the business had just moved into its now swanky ex-offices in that cultural vacuum that is Canary Wharf. They’d introduced hot-desking, with expensive Cisco IP phones that people had to log into separately from their PCs. Nobody bothered.
The pandemic has probably sounded the final death knell for the phone in business, Inter-organisational Teams and Zooms and Meets and sometimes even Webexs have replaced in-person and killed the last remaining vestiges of audio-only conferencing.
Today the phone is a lowest common denominator channel. But at some point, maybe very soon, it might become a channel which many struggle to access, in the way that fax did in the end.
As landlines become less common, and we continue to struggle with the physics of cellular networks (and the Faraday Cages that many buildings helpfully offer) assuming it’s more possible to phone over every other channel of communication will become flawed.
For organisations that still gear themselves around phone as the primary customer service channel this will pose challenges – for those who have built themselves around a channel-agnostic model, switching phone voice for WhatsApp voice or Meet voice won’t be a big issue – it’s just a more or less fungible channel.
But for those who have a monolithic model, built around the vagaries of the traditional telephone network, the lifting will be heavier. And that lifting probably needs to have started already. We’ll still need voice. And maybe expect video. Just not through a traditional phone line.
mmitII 
I still regularly use a phone. I have the same challenges as you with large quantities of steel in our house, plus poor reception on the higher frequency networks, so land line is often used (though we will remove the calling package as its not used so much these days).
My issue is not so much the redesign of business models to use alternative channels but the insufficient number of staff to properly service the existing ones. Web chat is often unavailable. Phone lines with long wait times due to “higher than usual call volumes” (“your call is important to us”). It’s not helpful for a recorded message to tell you to use an app if the app can’t help with your problem.