Today I bought a new pair of in-ear headphones with a built in mic, and I thought I would test them. So I took my corporate iPhone 5s and called my iPhone 6 whilst wearing the headset with it. To my amazement I could not only hear the iPhone 6 ringing in the earphones, but the calling iPhone 5 also appeared to be ringing as well. So I hung up and tried again. Same result. Now, how can a called phone automatically call back the calling phone whilst remaining ready to accept incoming calls? And how could the calling phone be calling and receiving a call at the same time? Seems pretty difficult... At first I thought maybe I had been hacked or was being bugged by the NSA. Better yet, maybe I had uncovered a really cool iOS bug! But it turns out the explanation is so simple I wonder if I might not be regressing mentally with each new iOS release. It's a feature many of us have tested (myself included), but I hadn't fully realized its ramifications. Yup, you guessed it, that feature is called continuity. The ringing sound was coming from an iPad lying under a pile of books. I had totally forgot about those continuity experiments I had conducted with Yosemite. 