LED Flash Alerts
When you receive an incoming call or text message (or other notifications), iPhone normally alerts you by a text tone or vibration if it's put into silent mode. With iOS 5, you're provided with another option. Buried deep in the accessibility Settings is a new feature that lets you use LED flash next to the rear camera to inform you about a call or incoming SMS.
Simply go to Settings -> General -> Accessibility and enable LED Flash for Alerts. That's it. Whenever you receive an incoming call or text message, the LED on the back of your phone will blink three times.
The LED flash alert only works when you put your iPhone in sleep and silent mode.
Custom Vibration for Contacts
Not only you can customize ringtone and text tone for any contacts, you can now set a custom vibration. So even you've put your phone in silent mode, you can identity the caller based on the vibration pattern.
To enable custom vibration, go to Settings -> General -> Accessibility. Scroll down until you see the Custom Vibrations option. Flip the switch to ON to enable it.
Once you enable the custom vibration, edit any of your contact and you should find a new option named Vibration. Tap on it and select your preferred vibration pattern.
If you don't like the built-in vibration pattern, you can even create your own pattern by selecting the Create New Vibration option.
These two features are specially designed for the hearing impaired. However, I think they're also useful for anyone who needs alternative alert method.
The original post was published on Simon Blog: How to Enable LED Flash Alerts and Custom Vibration in iOS 5