fm transmitter is not actually equal to radio...
radio function is to listen to radio station only such as hitz.fm...
but if i'm not mistaken..
fm transmitter is a function to let you broadcast your sound/songs through FM frequency..
example, u use FM 99.99mhz to broadcast your songs...then other ppl can actually listen to what you are broadcasting in a certain distance when they switch their frequency to 99.99mhz..
well,to conclude that, fm transmitter is also equal to radio but the difference is everybody can become a radio station...
if u need more info,wikipedia always your friend for it...
btw,nokia 5800 dun have fm transmitter..