Your iPhone's number pad is chiefly designed for making phone calls. However, it can also be used to input a handful of special codes that unlock extra features. Some are useful for everybody - such as showing exact signal strength - while others are handy for specific types of users - like displaying your call forwarding status. Here are six "hidden" codes that are worth checking out.
If you're an Apple user, you may have been experiencing problems lately, after it was discovered that a specific character from the Telugu alphabet caused a heap corruption and could crash devices and apps, including iMessage and third-party services like Twitter and Whatsapp.
Apple have now released a security update which fixes the problem for all four of its operating systems.
The above video comes from our colleagues at Business Insider. They're all pretty straightforward to activate - simply dial the digits and symbols as instructed and you should be good to go. (You can turn most of them off again by dialling the same number.) Our favourite has got to be the code that shows a more accurate reading of signal strength - handy for those patchy train commutes.
[Via Business Insider]