Hi Selintra,
I have uploaded three new mp3 tracks and did these commands:
/etc/init.d/asterisk stop
/etc/init.d/asterisk start
Then made an extension to extension call, put it on hold and it worked

So I assume that it will work when an external call comes in and is transfered etc. I will try it tomorrow. So if that's OK everything will be cool, I have my MOH tracks with comforting messages
Regards,
Del