Is it possible to play the radio through the speaker and not through the earphones? I've looked at the settings while the radio is playing, and the only option seems to be to save the current channel as a favourite.
edit The phone is a Lumia 610.
The FM Radio in Lumia 610 does not support loudspeaker (source).
For other devices, select and hold the station number, and select switch to speaker or switch to headset.
You still need to keep the headphones plugged in as the cord acts as the radio antenna.