After discussing Wireless Emergency Alerts last week, I thought I'd discuss another topic related to alerts on the iPhone — the Do Not Disturb feature of iOS 6. From conversations I've had with others, I know that there is some confusion about how this feature works, and it is important for iPhone users to understand when alerts can occur. After all, you don't want to be this guy who brought a performance of the New York Philharmonic to a halt, nor do you want a similar thing to happen to you in court.
[UPDATE 10/24/13: Note that Do Not Disturb works a little differently in iOS 7. For example, in iOS 7 it suppresses alerts even if you are using your iPhone.]
It is easy enough to activate the Do Not Disturb feature. Just open the Settings app and on the first screen you will see an option called Do Not Disturb. Turn it on to activate it. You can tell when the feature is activated because a moon icon appears to the left of the time at the top of your iPhone's screen.
When the feature is enabled, your iPhone will not disturb you (subject to settings discussed below). Phone calls to your iPhone will go straight to voice mail without the phone ringing at all. Thus, the feature gives you a way to silence phone calls, FaceTime invitations, alerts, and notifications.
You need to be careful about the Clock app, however. When it sounds an alarm, the alarm always goes off. This means that an alarm trigged by the Clock app will make noise even if the iPhone is in Do Not Disturb mode. It makes noise even if your ringer switch is turned off. I suspect that this is how most of us will want the function to operate; if you ask your iPhone to wake you up in the morning, you probably intend for an alarm to go off even if you don't want to be disturbed by other alerts. Just be aware of this and don't assume that the Do Not Disturb feature makes it impossible for your iPhone to make noise. An alarm that you set in the clock app to go off at a specific time, and an alarm that sounds when the countdown timer reaches zero, is going to make noise.
Even when Do Not Disturb is turned on, it only goes into effect when your device is locked — in other words, the screen is turned off. If you turn on Do Not Disturb while you are in court but you are using your iPhone such that the screen is on, then calls, alerts and notifications will still come through (and will make noise if your ringer/silent switch is in the up position). The point of the Do Not Disturb feature is to keep your iPhone quiet and unobtrusive when you not otherwise using it.
In the Settings app, just below the on/off switch for Do Not Disturb, you can tap the word Notifications and then, on the next screen, tap the word Do Not Disturb to change the settings for this feature.
One option is to automatically use Do Not Disturb on a schedule. I like this feature because I keep my iPhone in an iHome device next to my bed to charge it at night so it is very close to my bed. I don't want to be awoken by a simple alert such as a notification that I have a new email. Even if the ringer switch is turned off, many alerts will still appear on my iPhone's screen and turn on the screen for a few seconds — which can seem quite bright in an otherwise dark room at night — and some alerts such as incoming phone calls may also make your iPhone vibrate, which can seem quite loud in a quiet room. Thus, as you can see above, my iPhone turns on the Do Not Disturb feature automatically every night between 1:00 AM and 6:00 AM.
You can create two types of exceptions so that alerts pass through even when the Do Not Disturb feature is turned on. First, you can allow calls to ring through to your iPhone either from everyone (which somewhat defeats the purpose of the setting), everyone in your contacts (which helps guard against unsolicited calls), everyone in a subgroup of your contacts (you can create such groups using iCloud; click here for instructions), or everyone in your Favorites, which is the setting I have enabled. My Favorites on my Phone include people such as my close family members and a few folks at my law office including my secretary. If one of them calls me in the middle of the night or when I otherwise have Do Not Disturb turned on, I figure that there could be a good reason for it.
The second exception that you can create is for Repeated Calls. The idea is that if someone calls you from a number that is not in your exception list — such as a family member calling you from a pay phone — and they do so more than once, the second such call will go through because, presumably, it is important.
While I'm talking about the Do Not Disturb feature on your own iPhone, keep in mind that other people might use it as well. If you ever need to urgently reach another person on their iPhone, if your first call goes straight to voice mail, that might mean that the person's iPhone is turned off or it might mean that the person has the Do Not Disturb feature enabled. Thus, if your call is important, consider calling a second time to see if the call goes through because the Repeated Calls option is turned on.
If you're only concerned about blocking normal phone calls, one alternative is to use Airplane mode, which disables the cellular data service on the iPhone. Once airplane mode is turned on you can then turn WiFi on, but note that if you do so alerts such as iMessage text messages and emails will still come through, and even phone calls from other services such as Skype or FaceTime will come through.
There is always one guaranteed way to make sure that your iPhone doesn't bother you. Just turn it off. Hold down the on/off/sleep/wake button at the top right of the iPhone until you see the Slide to Power Off option, and then select that option. But if you don't want to shut down your phone and you find yourself in a place where you are supposed to be quiet, make sure that you understand the ins and outs of iPhone alerts so you can take the necessary precautions.