So THAT explains it (iPhone won't ring)
For a few weeks I've missed scads of texts and phone calls on my iPhone. Phone just did not ring. I thought it was my hearing that was going - or that AT&T had a service outage, or well, who knows why but my phone just WOULD NOT RING!
Finally googled. You know, if you have a picture of a moon in the upper right corner (I thought it was showing me the present phase of the moon but a tip-off should have been it was always the same pic) but if you have that picture, it means DO NOT DISTURB is on, and it means just what it sounds like. Easy to turn off (and apparently ON, inadvertently). Swipe UP from home screen and you'll see the icons for plane mode, wifi, bluetooth, DO NOT DISTURB and portrait orientation lock. Sure enough, my phone has been in DO NOT DISTURB mode for weeks now. If you tried to call me and I didn't pick up, I was not screening you. If you call me NOW and I don't pick up, I'm probably screening you.
"I'm no Einstein."