The big problem for this model of music provision, is mobile coverage and data plans. It's the phone companies that need pushing into the 21st century.

One chap was phoned by the PRS and was found to be listening to music at work. He informed them he composed the piece and was the sole artist. This cut no ice, with the PRS. (I suppose he might possibly listen to illegal music, so he should be presumed guilty!)

Another incident (2008) relates to the sole owner and lone worker in a garage in Nottingham being told he had to pay £150 to listen to the radio. see http://news.bbc.co.uk/1/hi/england/nottinghamshire/7671215.stm

Even if I listen to my MP3 player through headphones, my company is liable to pay for a licence! Perhaps I'd have to join the smokers outside for my quick fix of some illicit Pink Floyd.