For me it is fairly simple - usually texts in my company are higher urgency, location agnostic, communication. Only reason I would text is I need someone sooner than they see an email/Lync message, but I don't need them urgent enough to interrupt with a call. "I'm running late from this meeting, can we delay?", "you ok for lunch in 5?" etc. people typically respect that rough, unexpressed, protocol.
I've been "on call" for a while before, and part of the solution is to deal directly with that. Anything app that thinks it has the right to pop up notifications whenever the hell it feels like it (and why is "3am" so often when they feel like it?) better have a setting to undo that easily found, or they're in for a rude uninstalling. Anything else that thinks it gets the priority interrupt had better be prepared to discover it doesn't.
Because I need to save that priority interrupt for the actually important "site down" notice. I was getting a visceral twitch whenever I got a text because having the same alert for "CARTHAGE IS BURNING PREPARE TO SPEND HOURS FIXING IT YES I KNOW IT'S 2AM" and "hey whats up dude" was not working for me.
I'm not on that call anymore, but I've kept the habit of keeping everything away from that level of interrupt. If it's that important, pick up the phone and call me. Provide social proof of its importance by putting your own attention into the conversation. (Which, of course, can only be done by a real human.) Otherwise, you're not that important and you can deal with a delay.
Also, I work I higher education, where things move slowly. Although we don't have an assumption that after-hours emails will be replied to until the next business day, any delay of a day or more can cascade to far more delay on the other end(s).
- Privacy/InfoSec - Forgetting to change status - Meaningless status states (Away was never really that accurate or meaningful) - Extra messaging friction
I've found that it's usually just a few certain types that expect instant replies. It doesn't require too much time for them to get that I respond when I can. The same rules do apply to everyone, but I'll deliberately delay responses at times so as not to feed the expectation of the reply-needy. With email, I have set times to review and reply.