16.10. Phone

These settings have to do with your address book, call management, and other phone-related preferences.

• International Assist. When this option is turned on, and when you're dialing from another country, the iPhone automatically adds the proper country codes when dialing U.S. numbers.

• Call Forwarding. Tap to open the Call Forwarding screen, where you can turn this feature on or off. See Section 3.5 for details.

• Call Waiting. Call Waiting, of course, is the feature that produces an audible beep, when you're on a phone call, to let you know that someone else is calling you. (Section 3.4 has details on how to handle such a traffic jam.)

  If Call Waiting is turned off, then such incoming calls go directly to voicemail.

• Show My Caller ID. Ordinarily, other people can see who's calling even before they answer the phone, thanks to the Caller ID display on their cellphones or some landline phones. If you'd feel more private by hiding your own number, so people don't know who's calling until they answer your call, turn this feature off.

• TTY. A TTY (teletype) machine lets people with hearing or speaking difficulties use a telephone—by typing back and forth, or sometimes with the assistance of a human TTY operator who transcribes what the other person is saying. When you turn this iPhone option on, you can use the iPhone with a TTY machine, if you buy the little $20 iPhone TTY adapter from Apple.

• SIM PIN. As noted on Section 1.2, your SIM card stores all your account information. SIM cards are especially desirable overseas, because in most countries, you can pop yours into any old phone and have working service. If you're worried about yours getting stolen or lost, turn this option on. You'll be asked to enter a password code.

  Then, if some bad guy ever tries to put your SIM card into another phone, he'll be asked for the password. Without the password, the card (and the phone) won't make calls.

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  And if the evildoer guesses wrong three times, the words "PIN LOCKED" appear on the screen, and the SIM card is locked forever. You'll have to get another one from AT&T. So don't forget the password.

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• AT&T Services. This choice opens up a cheat sheet of handy numeric codes that, when dialed, play the voice of a robot providing useful information about your account. For example, *225# lets you know the latest status of your bill, *646# lets you know how many airtime minutes you've used so far this month, and so on.

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  Tip:

  The AT&T My Account button at the bottom of the screen opens up your account page on the Web, for further details on your cellphone billing and features.

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