Basically, what we wanted was to push voice messages or sound advertisements (i.e. safety related) either into the dial tone, dnd tone, ringback tone and music on hold tone. Later on, we decided that it's more practical and convenient to implement it on the ringback tone. So we wanted the caller to hear certain "voice + music" looping continuously, instead of the tradition ring.
We pre-recorded very short, one sentence voice message related to safety. Then by using an audio editor, we inserted a ring after 2 seconds, then another message again, then inserted a ring, and so on and so forth.
On the HiPath Commander, ADD-SSC:1-5-121-5,EXTANN,RNGBK;
The 1-5-121-5 is the PEN of an analog extension where you would insert the external music/sound source.
I connected an analog telephone and right after the ADD-SSC, the analog extension rang. I had it off-hook and used the handset telephone cord and connect it to the speaker output of my laptop (where I was playing some classical music + voice message looping continuously with Windows Media Player). I had to solder a 3.55 mm audio plug with the telephone cord (the outer pins were the mic input).
On-hook the analog telephone to soft reset the PEN. Then when you call an extension, you will hear the music + voice message. This also goes true for external callers.