℻ numbers are dropping like flies. This is a disaster for the very few of us who will not lick the boots of Microsoft or Google, unlike the 99%¹ of the population who is happy to use email (which traverses MS or Google servers in a vast majority of non-p2p comms).
So FAX numbers are disappearing. Some are removed from websites and stationary (letterheads), but still exist. Some fax numbers persist in publications, but the plug has been pulled. Not enough people are using fax to say “please plugin your fax machine”.
the race condition
Corps, NGOs, and govs likely ditch the fax after it idles for a long time with no activity. It’s a use-it-or-lose-it scenario. Part of the problem is someone’s rare will to send a fax is hindered by lack of info. If we had reliable access to fax numbers, we could do our part to keep them active.
open data remedy?
When a gov has an open data policy, one possible solution is to make open data requests for the fax numbers of gov offices.
previous posts
¹ made-up figure obviously, but likely accurate enough nonetheless

Are there things you have to fax and cannot use physical mail for?
In some cases, snail mail is just too slow for the situation at hand. Speed is the only thing that makes fax irreplaceable in some cases.
In most cases, fax is much cheaper than postage. So I’m always grateful when I can send a fax… so I don’t burn through stamps so quickly.