A couple of months ago, I started having a problem with my iPhone. When certain people called me, they went immediately to voicemail — no ring, no vibration, no notification whatsoever until they texted to tell me they couldn’t get through.

It wasn’t everyone, just a select few, and I couldn’t figure out why. I checked every possible setting on the phone, including “Silence Unknown Callers,” “Call Forwarding,” “Call Waiting,” and several others. They were all turned off, as they had always been.

The reason this was incredibly annoying was that these were the people I speak with the most often who are all on my Favorites list in the phone. My calls to them went through, but not when they called me. What the hell?

A few days ago, I found a built-in diagnostic on my iPhone. When I ran it, the report said the problem was not with Apple’s software, but with my carrier, AT&T. I wasn’t surprised Apple had installed software which deflected the blame onto someone else, but okay, I decided to play along.

Having been a customer of AT&T for decades, this was not the first time I’ve had issues with them. And I know from experience that calling their tech support line for help is like opening the door to twenty-seven layers of hell, each one more frustrating because as they pass me from one person to another, I always have to repeat the problem and tell them the steps I’ve already taken which have failed. Then they each make me go through those same steps — only to have them fail again.

Instead of calling, I thought I’d talk to a human being at the AT&T store in person. I knew this was a long shot. My wife even warned me that those folks aren’t tech support experts, the equivalent of Apple’s Genius Bar employees. Rather, they are sales people. If you want to buy a new phone or set up a DirecTV account, they can help. But a technical issue? Not in their wheelhouse.

I decided to give it a try anyway and made an appointment.

When I arrived, an employee took me immediately, and within seconds of me explaining what I needed help with, he told me he wasn’t really a tech support person. But he looked through my phone and, yes, went through every option I’d already tried. Then — oh, no, here it comes — he thought it would help to call AT&T tech support. He saw me roll my eyes, but insisted he was calling a higher level of tech support than the ones I had reached.

Yeah, right.

The person who answered was just as useless on this matter as I expected. But when he put us on hold for a couple of minutes, since that call was on the AT&T guy’s phone, I picked up my phone and looked one more time to see if I’d missed some hidden thing.

On a whim, I tapped the Focus section of Settings, where there’s an option called Do Not Disturb, which allows users to block incoming calls and notifications on a set schedule. I have used DND and found it pretty effective. I preferred it to turning on Airplane Mode, because Do Not Disturb let me specify people (family members and my lawyer) whose calls or texts would get through (e.g. in the case of a middle-of-the-night emergency).

That’s when I noticed that, under the scheduling option for Do Not Disturb (I had mine set to be active 11pm-8am), was a toggle switch for Smart Activation. This had to be a new feature added in one of the recent iOS updates, because I’d never noticed it.

So, what is Smart Activation? Here’s what it says on my iPhone:

Automatically turn Do Not Disturb Focus on at relevant times throughout the day based on signals like your location, app usage, and more.

In other words, the iPhone was deciding on its own when to turn on Do Not Disturb, thus blocking incoming calls and notifications at random times — without my knowledge!!

As soon as I turned off Smart Activation, I asked several people who’d had trouble reaching me in recent weeks to give me a quick call as a test. Happily, my iPhone rang every time.

Finally, problem solved!!

But the question remains: who thought this was a good idea? It’s a classic example of designers not being users. I honestly can not conceive of any reason for Smart Activation to exist.

I felt like Sigourney Weaver expressing her extreme irritation at having to move through The Chompers in the sci-fi satire, “Galaxy Quest.” I’m not going to bother explaining the plot, but I think you’ll understand when you watch this scene…