I found an article about London pirate radio stations first published in Sunday Times magazine in September 2003. In it the author, Matt Munday, tells how mobile phones and SMS are being used at Xtreme FM to keep contact with listeners:
A show is in progress, the DJs taking turns to mix records together and exchange banter in a cockney pirate patois. The music veers from chunky hip hop to saccharine R&B – like most contemporary pirates, Xtreme champions “urban” sounds, a term that originated as a euphemism for black music. When not DJ-ing, they fiddle with their mobile phones: texting, reading texts, taking calls. Everyone has a top-of-the-range handset.
There is a studio mobile too. It vibrates every few seconds like a faulty alarm clock, as listeners call and text. Scrolling through its inbox, I notice scores of “missed calls”. Big N explains that this is how pirates gauge a record’s popularity. If listeners like a tune, they call in and then ring off, so the studio mobile registers a “missed call”. This costs callers nothing. If Xtreme receives over 20 missed calls from different numbers before a track ends, the DJs play it again. This is why teenagers listen to pirate radio: it’s interactive in ways legal stations can’t match.