Rather it depends on what codec is being used and in what order the audio sources were added to your server.

It is not necessarily the IP address set in the MOH server you see above or even related to the number of the audio source in use. Now verify what multi-cast IP address your music will utilize. The switch where the phones and voice gateway were connected at the remote site did not even have multicast routing enabled. Because the phones and voice gateway used for streaming the MoH file were on the same subnet at the remote site, I only enabled support for multicast routing on the voice gateway itself. Note: You do NOT need to support multicast traffic generically across the network or across the WAN. MRGL used by remote devices that includes multi-cast MRG from above You then need to create and / or assign a MRGL to the trunk, device pool or other that includes the MRG configured above. Because only one stream is needed, network bandwidth is over-utilized and network congestion can eventually result. Thus, when it encounters multiple streams sent to the same multicast group address (even on different port numbers), the router forwards all streams of the multicast group. Routers have no concept of multicast port numbers.IP network routers route multicast based on IP addresses, not port numbers.This has the potential of saturating the network with unnecessary traffic because the IP phone is capable of receiving only a single MoH stream. Therefore, if all the configured codecs for a particular audio stream transmit to the same multicast IP address (even on different port numbers), all streams will be sent to the IP phone even though only one stream is needed. Cisco IP phones have no concept of multicast port numbers.IP phones placed on hold join multicast IP addresses, not port numbers.Note: You should configure multicast audio sources to increment on the IP address and not the port number (see server configuration above) because:

Cisco call manager download moh file