The tour continues with the top-left corner of the iPhone. Here’s where you
plug in the white earbuds that came with your iPhone.
This little recessed hole is no ordinary 3.5-millimeter audio jack, however. It
contains a secret fourth pin that conducts sound into the phone from the
microphone on the earbuds cord. Now you, too, can be one of those executives
who walk down the street barking orders to nobody in particular. The
iPhone can stay in your pocket as you walk or drive. You hear the other person
through your earbuds, and the mike on the cord picks up your voice.Incidentally, the tiny microphone nodule on the cord is more than a microphone;
it’s also an Answer/Hang Up clicker, you can use any standard headphones with the iPhone — a welcome
bit of news for audiophiles who don’t think the included earbuds do their music
justice.
The catch, however, is that the molding around the iPhone’s audio jack
prevents most miniplugs from going all the way in. You may be able to get your
headphones to fit by trimming its own plastic collar with a razor blade—or you
can spend $10 for a headphone adapter (from Belkin.com, among others) to get
around this problem.
