Sorry for the late reply...

Calls and texts aren't really a thing any more, and most people communicate through apps instead. That means that even without a phone, there's a pretty good chance you can still be included if you have access to a computer at home.

I find this varies a lot within different social groups ... some people I know use different apps some people don't use anything other than SMS/iMessage and/or maybe Facebook messenger.

My friends and I definitely communicated with Skype and things like that. I just never really had the chance to "grow my social network" if you will as a younger teen. Like summer 2009 I did a summer gym thing (my school let students take gym in the summer before high school for the high school PE credits and lots of kids did) ... if I had a cell phone there's a good chance I might have made connections with kids that had interests other than "get on the computer and play video games (and associated 'nerdy' interests)."

So in my mind, this means that not providing a phone doesn't cut them off, it just delays communication. That means they'll have less of a chance to become addicted to all the SM BS, while still being able to be included in things. I think that's a healthy boundary to set.

That could be fair; it just kind of depends on what their peers are doing. I'd also caution against artificially creating hard barriers that won't be for them later in life. My parents didn't lock the fridge they just said we couldn't have ice cream more than one time a week. It was ultimately on us to be able to honor that agreement.

Of course that wasn't a bullet proof "solution", I'm sure we snuck some ice cream here or there ... and I'm sure we got caught at least one. But, IMO that's just part of being a kid and a couple of bowls of ice cream when we broke the rule didn't hurt anything, the rule still did its job (keeping our diets tilted towards good).

That said, absolutely none of my friends communication during HS or my communication in college was productive. We didn't "discuss homework" or anything related to school, we merely arranged hangouts and flirted, with a little gossip to round things out. I highly doubt things have changed much, because that's just what kids do. When I was young, cell phones weren't a thing, and my sister spent hours on the phone talking about nonsense with her friends. That's just how teenagers work, if they're talking to friends, they're not talking about school work.

I think this varies too. Of what I remember of college, sure the vast majority of stuff was non-school communication. However, there definitely was communication over projects (especially if I was doing something with friends vs random people in class).

That said, I'll certainly be paying attention as my kids get older.

I think this is the biggest thing. Like, nobody can tell you how to parent your kid and I'm not trying to tell you what's right. I'm just saying, my parents took a hard line stance on this, based on some made up rules about what I should or shouldn't have that was way different than what nearly every other parent was doing. I didn't have the gumption (arguably due to a mostly unrelated, hidden, depression that my parents attributed entirely to "teenage angst") to advocate for that access or ask for help and largely just accepted my situation as the best I was going to get.