Can you listen to music without paying?

In the car I normally listen to music from my iPhone but when I run out of 3G I can't because I don't have Wi-Fi. I use a app called imusic because in my iPad I can use it without Wi-Fi but I can't with my phone so is there a way I can listen to music from my iPhone without Wi-Fi and without paying to download music?

You could sync music onto the device itself using iTunes.

There are several apps on the app store that helps you search and download music. You can also download music on your computer or laptop and then transfer it to your device.