Exact same thing happens to me, all the time. Verizon user on a traditional post-paid plan, with an iPhone 15 Pro Max, in the Los Angeles area.

My phone will show as having full service, usually it displays as “LTE” in the top bar while at home whether or not I’m connected to WiFi, as soon as I step outside of my building and head 25 feet in any direction 5G or 5GUW seems to take over.

It’s strange, I’ve always gotten missed calls over the many years I’ve been with Verizon (over 20) and I’m not entirely sure exactly when I noticed that people were increasingly telling me they called me, while I had zero idea or any way of knowing whatsoever. At best, I’d get lucky and they were one of the rare people still leaving voicemails these days, and an alert might show up for that at some random point.

It got bad enough that after trying everything else, I even went and picked up one of those “network extender” boxes the carriers have from a Verizon retail store, out of a sense of desperation hoping it might help solve the issue, although I knew beforehand that almost surely it would not. Which was the case, of course.

I wish I could say I had any idea as to what is actually causing this but all my attempts to pin down the root cause have proven to be a waste of time. A very frustrating waste of time. Worst of all is that as far as I can tell, it isn’t an issue that’s isolated to any single carrier, subcarrier, phone model, physical location, and so on. While there do appear to be some patterns here and there, it’s largely random and I don’t know if certain carriers have this issue worse than others but Verizon is frequently one mentioned. Whether or not that’s due to their popularity, my noticing it more because I use Verizon as well, or because it’s worse with them, who knows? Maybe someone reading this, lol.