Oh yea, you sure hit a sore point. Cisco told me it wasn't possible. So...here's how to do it.
Find the "Send H225 User Info Message" Service Parameter and change it to "Use ANN for ringback" which references the Annunciator since the Gateway is hard-wired to play those beeps and doesn't understand anything else.
Let me know if that works...to be honest, I went through so many steps with TAC that my config is a little messy with what I'm sure is a lot of orphaned steps. You may have to create a silent .wav file to set as the MOH source, but I think the Service Parameter should do it. If it doesn't work, I'll go through some other stuff. It's been a while though so I have to rehash it.
Sure. On a Windows computer go to Start - Programs - Accessories - Entertainment - Sound Recorder.
Unplug your microphone if you have one and start recording. You've got yourself a silent .wav file.
But to clarify, if you have an H.323 gateway, the beeps will not go away just because you used a silent wav file. Those beeps come from the gateway itself, not the MOH server.