The version of mpg123 that is installed by default is 0.66. I had several problems with streaming music on hold, the fix was to install a newer version of mpg123.
Here is a workaround to get a newer version:
wget http://apt.sw.be/redhat/el5/en/i386/rpmforge/RPMS/mpg123-1.9.1-1.el5.rf.i386.rpm
yum install esound-devel
yum install libtool-ltdl
rpm -i --force mpg123-1.9.1-1.el5.rf.i386.rpm
I think the more permanent solution would be to either compile from source and include it in the ISO image or possibly even host it on one of the FreePBX repositories.
Other than that… really like it so far! Think I’m going to replace my Asterisk Now install with this…