How are other people supposed to know that it's not okay for you right now because you are at dinner?
People get lazy and just use the "whole group" message rather than send it to those who are working today. And it's much like my problems with Android vs iOS: there are twelve people in this group, eleven of them have iPhones. They are not all going to install and use a separate messaging app for business than for personal communication, especially as iMessage is nominally E2EE. I could adapt or just be completely marginalized. So now twelve have iPhones.
This does not sound like an impossible stretch, works on more device types, and in the case of Slack or Teams can also be configured for HIPAA compliance (which while you don’t call it out, seems like it may be useful). Tens of millions of people use a chat system for work distinct from their personal friend groups, even if the venn diagram is a circle.
We do not have desks. Nor do we have offices.
I'm an anesthesiologist; I work where the patient and the surgeon are.
I like Apple hardware, but try to avoid its first party apps as much as possible due to that.
I realize that I live in an unusual life vis-a-vis most HN readers. I do not work in tech, and I never have. I'm a physician: specifically, an anesthesiologist. I have always enjoyed tech, and I'm certainly miles ahead of most of my colleagues on that. But. Remote work is not possible. Relocating involves getting a new license to practice medicine (3-8 months), getting accepted by the medical staff of any hospital or surgery center you want to work at (~2 months after license is secure and job contract is signed), and all the usual stuff.
So I cannot not answer any number that isn't outside the US system when I'm on call. I can't silence the phone when I'm on call. I can't ignore messages. But we're a partnership, so there's no HR to file a complaint with when someone banters on a business channel, and I can't order them to do something any more than they could order me.
Not doubting your description of your situation, and it does sound extremely stressful.
There are so many apps/services available for this exact purpose that can alert (with or without sound, per user choice) through iOS's and Android's "do not disturb" mode, can call or text several numbers in sequence (useful in places with weak signal but a landline) and much more.
The multiple-dial might help if we had a fixed location, but we don’t. Getting boosters or microcells in dead spots is just now happening, but the IT department could also enable WiFi calling, which they block.
It’s a long litany of hair-pulling.
If I were in a group chat with people both joking around and sending messages requiring urgent responses, I'd let them know to either cut the banter and keep the channel clear, or contact me otherwise if they need my urgent reaction. Letting people hold my attention hostage like that would drive me crazy.