From GNU Telephony
All software available from or used in GNU Telephony is licensed as free software. Many of our software packages are distributed as part of the GNU Project. Most of the packages we provide and use are licensed using the GNU General Public License and we are in the process of migrating all of our packages to the GNU GPL Version 3 or later.
Downloads available through GNU Telephony include both source tarballs and pre-built RPM packages. The pre-built RPM packages may be installed with YUM or similar tools common on RPM based GNU/Linux distributions. The source packages we provide and use generally are OS independent.