If you have an iPhone, this hack might come as a surprise.
There's a clever way for you to work out who's calling before you've even taken your mobile phone out of your pocket. And it even works when you've got your phone on silent.
Many phones let you set custom ringtones for specific people so that you know you're significant other is calling when your phone starts playing their favourite song. And while you can do that on iPhones too, you can also do something even more impressive.
