playing long mp3 in short time

hi ,
I have an mp3 of 1 minute duration & I want to convert it to sound file (for my mobile ringtone) that plays the whole content in 30 seconds . How can I do that ?

If you want to make it play faster, use the Change Speed or Change Tempo effects.

Forgot to reply.
Better late than never.
Change tempo allowed me to elongate or shrink voice clip with accuracy of 1/100th of second.