it is a way of identifying a piece of music you have no idea what it is.
Try this :
1) turn on the radio
2) Get mobile and dial 2 5 8 0
3)hold mobile to speaker and press send
4)hold to speaker for 20 secs or so (you will see the phone has hung up)
5)wait a little bit
6)recieve text message giving you the song details.
easy peasy