When the phone breaks, use a Morse code mirror
Morse code has been around for years. It is the series of dots and dashes that can be interpreted in to words so that messages could be passed around in the olden days. Who knows Morse code though? You might be familiar with the good old dot dot dot dash dash dash dot dot dot (means SOS). If you are not in the special forces and are not 80 years old or more then you probably dont know much more then that.
The Morse code mirror has all the dots and dashes etched on to the surface of it allowing you to move the mirror around to someone in line of sight and get the signal over to them across the busy beach so that they know they need to grab ice cream on the way back.
The Morse Code mirror is 0.25mm thick and made of stainless steel. It is customisable and costs 7.95 GBP. However, I do not have a clue what aspect of it is customisable. But for 7.95 you have your self a nifty mirror.