Is the on-hold music which comes with Asterisk, royalty free?

Can anyone possibly confirm whether or not the music which comes with Asterisk, is royalty free?

Howdy,

The sounds tarballs contain a license file, the text of the license file reads:

These files are distributed under the Creative Commons Attribution-ShareAlike 3.0 license through explicit permission from their authors.

The license can be found at:
http://creativecommons.org/licenses/by-sa/3.0/

The files were sourced from http://opsound.org.

Many thanks Malcolm. I’ll check out that license.
Regards
Ray

Can’t say I understand this one:
http://creativecommons.org/licenses/by-sa/3.0/

But this one seems to confirm that it can be used freely:
http://opsound.org.

Regards
Ray