Am I correct in my finding that a MOH server can have either multicast or unicast streams, but not both? Well, it can have both, but only the multicast steam will work? This appeared to be the cast with CCM 4.1(2) and 4.1(3)sr1.
My work-around for the moment as I have some devices that won't support multicast is to have one CCM configured as multicast and the other as unicast and have two different MRG to put the MoH resources in and keep the multicast MoH-MRG out of the MRGL for the devices that cannot support them.
This is not at all correct. A single server can support both unicast and multicast MOH simultaneously. We do it all the time.
To do so:
1) Configure your server and audio source(s) to support multicasting.
2) Enable any additional codecs required in Service Parameters for the MOH server's IP Voice Media Streaming service.
3) This one is critical - create two (or more) Media Resource Groups. Select "Use Multicast..." for one group, and do not select it for another. When finished, you should have at least two groups, one with multicast support, and the other without it.
4) Create a couple of Media Resource Group Lists. Place the Multicast MOH group in one, and the non-multicast group in the other.
5) Assign the MRGLs to the appropriate devices.
Again, all CCM MOH servers support unicast, but you have to enable multicast support on the server and audio source. This ADDs (not replaces) multicast support to the existing unicast support on that source and server. And then you choose who gets multicast by the MRG/MRGL combination. MRG settings override Server and Audio Source multicast configs and give you the flexibility you are looking for.
The only limitations you could run into are codec support (addressed in service parameters) or too many unicast streams for the server (addressed by adding servers.)
Let me know if this helps by rating the post.