I'm not much of a mobile phone type of person, so please excuse my ignorance. Recently bought a Sony K610i, I have noticed that all the time the phone is switched on it emitts a flashing green light from out of the top of the phone, (not the front the top). As I've not seen any other phone do this, including other Sony phones, I was wondering if this was correct and if so why it does it on this model of phone and not others.