For any Asterisk deployment, it often needs on-hold music or vivid ring tone music. Free music is a good choice for these purposes.
"Free music is music that, like free software, can freely be copied, distributed and modified for any purpose. Thus free music is either in the public domain or licensed under a free license. It does not mean that there should be no fee involved. The word free refers to freedom (as in free software), not to price." [1]
The following musicians provide free music licensed under Creative Commons: By Attribution 3.0 (http://creativecommons.org/licenses/by/3.0/)
Kevin MacLeod
http://www.incompetech.com/m/c/royalty-free/
Jimmy G
http://www.jimmyg.us/JimmyGMusic/MusicDownloads/tabid/99/Default.aspx
Jonathon Roberts
http://www.jmtr.com/jmtr-royalty-free.html
References:
[1] Free Music, Wikipedia, http://en.wikipedia.org/wiki/Free_music