Ive worked security at many gigs and festivals over the years, and one that seems relevant to this thread is the 3 day event Oasis put on at Eaton Park a couple of years back. No ones phone would work in the arena, and the signal only got through once you were stood over by the fence, a good hundred yards from the stage. I asked a techie if there was a reason for this, and he said they were using a commercially-bought network blocker, to stop punters live streaming the gig straight on to youtube etc.
As for taking photos with your phone, security won't really bother unless you're within arms reach of the pit, and the entry search is usually for 'pro' or interchangeable lenses.
The paps down the front would get upset if punters took better snaps than they do
wouldnt be hard to outdoo pap photographers tho would it
thanks for all the advice everyone, gonna take my chances n slip a dslr with a 300mm lens
"" Ooo er is that a lens in your pocket or are you pleased to see me ""