Early thirties here: my friends and I do not call people except for older relatives on occasion. We've kept our phones on vibrate for a decade and a half now.
We do, however, know our own phone numbers, and asking a cute stranger or a new friend for their number is still a thing.
For younger group, you don't generally know or give out your number in the first place for person to person communication, which means that for the rare chances you are expecting, say, a medical call once a quarter or less, it's a scam. I don't know my best friend of 10+ years phone number but I can reach them in multiple ways.
If you're older the ratio probably tips it further into the "likely to be a valid call" I'm guessing.
I receive something on the order of one legitimate call every 5-8 months, everything else is spam/scam. There is absolutely no point in me accepting a call.
A formal phone call is generally synchronous, not asynchronous. It is extremely blocking behaviour and I hate it. Joining a group call with a few friends or even just 1-2 other people on discord or whatever else that you can drop out at any time without notice is a different type of "mood" and completely different set of standards. You can drop in and out in seconds, pop in to say hi and leave while you have your airpods in on while riding bart, , or spend hours just discussing dumb shit, etc.
Not the GP, but my phone is almost always on my desk (when working), on the coffee table (when at home), in my pocket (when out and about), or hooked up to my car giving me music. I only rarely miss a call even though, other than when it's connected to the car audio system, my phone only vibrates when I get a call or message. It's pretty hard to miss. A ringtone would only help if I kept it in a separate room, which only happens when I forget it in the basement gym.
At least for me, most incoming calls are spam. If it's important, I will either anticipate it or the caller will leave a voicemail. In the past several months, I think I've received one unanticipated call from a friend.
Here's the thing, where I live (Canada) spam calls have become so bad that (unless you're in my contacts already) I almost never answer the phone. The scams aren't even in English most of the time :/
Actually it's filtered so that only 3 or so of my contacts get through the dnd.
*Scheduled calls / expected calls from specific companies are my one exception.
I don't know how well this generalises, but in my sample size most people including myself don't even know our own phone number if asked. You don't exchange phone numbers. You might hold out your phone for the other person to scan your Snapchat QR or tell them @hn2022 and a platform like instagram. If you say hn#2022 people know automatically which platform that is. A sizable amount don't even have phone numbers and opt for data plan only for cost savings if paying for their own plan.
We do, however, know our own phone numbers, and asking a cute stranger or a new friend for their number is still a thing.