Emergency services. You can't call an ambulance via Zoom. Even if 911 supported Zoom, Zoom probably won't support 911 because they don't want to be held liable if people die because of a Zoom outage.
Earlier this week, the FCC Fined CenturyLink $400,000 and West Safety Communications $175,000 for a multi-state 911 outage that occurred in August 2018. To resolve the dispute, both companies also entered into a Compliance Plan.
https://www.beyondtelecomlawblog.com/fcc-fines-companies-for...
Not surprisingly most vendors also dropped support for this merely in favor of lock-in.
But I've lost count at the number of times all these things have failed me at work and in my personal life, where I've had to resort to "telecom" (just making a voice call, although I do know it's still VoIP, but there are different quality of service considerations and carriers always prioritize these)
Not to mention rural communities without adequate cell service.
I'm also somewhat surprised there isn't a standard for this (maybe one is being worked on) so that all services and register for the standard to let me connect.
Further, I'm surprised there isn't work to let me register some contact info in a global way. As it is, when I move, I have to contact 15-30 companies and update my address. Why I can't I just do that in one place and the companies can use the info live?
Yes, I get here are all kinds of privacy issues. Still, there must be some solution. For example, id service providers let me login, change my address, and then select which companies that I've registered to that id get my new address, etc.... I'm going to tell them anyway, just make it less tedious to do it.