They're taking WHAT?!
You mean to tell me people actually take mobile phones to pot fest ..... er ..... pop festivals?
I despair of this generation, really I do.
In my day, we may well have dreamed that some sort of two-way radio might be a useful thing to take to a festival. No doubt there were even some folk resourceful enough to have improvised devices for senselessly wasting 9-volt batteries using naught but old tobacco tins, Veroboard, coils painstakingly wound on ferrite cores with the aid of a Qualcast Clipper Double Pinion hand-drill and parts scavenged out of broken wireless sets. Some of which might even have succeeded in propagating a signal further than the unassisted voice -- for just a few seconds before the batteries became irretrievably spent.
Besides which, all decent festival frolics used to involve getting naked. And where on earth would you put a mobile phone then, eh?