A new feature in iOS 11 will make it easier than ever to call for help if you find yourself in an unsafe situation. Emergency SOS will call contacts and local emergency services after the sleep/wake button is pressed five times in rapid succession.

Here's what you need to know to get started.

Medical info, emergency contacts and SOS

Screenshots by Jason Cipriani/CNET

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To customize how the SOS feature works, go to Settings > Emergency SOS. There you can view who is added as your emergency contact, and enable automatic calling.

Any emergency contacts listed on this screen are there because you've added them in the Apple Health app. If you want to remove or add another person, you can do so from the same app.

A potential downside to enabling automatic calling is accidental triggering of the SOS feature. All it takes is five rapid presses of the sleep/wake button to trigger a call, and there's no guarantee that won't happen in a pocket or purse. I recommend leaving the Countdown Sound option enabled, this will cause an alarm to play for three-seconds once the SOS feature is triggered, giving you a chance to cancel the call.

Without automatic call enabled, you'll need to slide a button across the display before a call will be placed.

Touch ID side effect

Screenshot by Jason Cipriani/CNET

Another aspect of the new SOS feature is, when triggered, your iPhone will disable Touch ID or Face ID and require your passcode before it's enabled again.

Why is this a big deal? If you find yourself in trouble with law enforcement, they can't force you to give up your passphrase or PIN code to your device. They can, however, force you to use a fingerprint or scan your face to gain access to your phone.

How to help others

Screenshot by Jason Cipriani/CNET

If you're in a situation where someone needs help and they have an iPhone, press the sleep/wake button to bring up the SOS feature and slide the Medical ID button to the right. Odds are you've already called for help, but using this feature means you can find the person's emergency contacts to let them know what's going on.