Convert 3GP to MP3

This is quite  a simple procedure but requires a little bit of setup:

1) Download the zip version of Audacity and unzip to desktop
2) Download the LAME MP3 zip from here and copy the contents to the plugins folder in Audacity (used for output)
3) Download the FFmpeg zip plugin from here and copy the folder contents to the plugins folder in audacity (used for input of the 3gp file)
4) Configure Audacity to use the FFmpeg plugin as shown here 

Now all you need to do is:

1) drag and drop the 3gp file onto audacity
2) click file -> export and save it as a mp3