To compound matters, this permission grants people the ability to disrupt you no matter when or where you are—including now on your computer. The best you can do is control to whom you give your phone number, but even that’s no deterrent, as anybody who’s ever received a spam text message can attest. Even further, with iMessage, you’re available not just to anybody who knows your phone number, but also to any person (or, potentially, service) to whom you’ve given your Apple ID—which for many users is also their primary email address.

Contrast that to instant messaging, which has long provided granular permissions. It’s easy to block users, limit access to just those on your buddy list, or even create a strict whitelist of the very few people you want to be able to send you instant messages. It’s also easy to create multiple usernames, if you really want to, say, keep a strict division between your work and personal lives.

Instant messaging is inherently a stateful system: You’re online, you’re away, you’re idle, you’re invisible, you’re offline. Most importantly, get to dictate your status. For instance, I mark myself as away when I’m at lunch; sometimes——I’m still at my desk; I just want to dissuade people from expecting a prompt reply. Sometimes I’m not at my desk at all, in which case IM functions more as an answering machine—messages for me to respond to at my discretion, when I have time.

Text messaging, on the other hand, is stateless. You’re always available, whether your phone is off or on, or whether your phone is on your person or not. With that statelessness comes an expectation that you should always be available, because, well, you’re getting my messages, aren’t you? This is more psychological than technological, but I’d wager most of us have obsessed over whether or not someone has actually received or read our text message—and, if so, why they haven’t responded. In fact, that’s one concern shared by teenagers sending messages to their crushes and parents sending messages to their kids alike.