• Unified CME streams MoH only in G.711 format.
• Each MOH stream requires a MTP that is software based and consumes router resources
• SIP Phones require CUCME 4.1 or above
• A live feed via an E&M port
• If multicast MOH is not configured, default behaviour is that internal phone will hear beeps whilst FXS and PSTN calls will hear MOH. This is because default ephone is configure to MOH via multicast.
• Audio file
  • G.711 mu-law or a-law
  • .au or .wav
  • 8 bit 8kHz

• Activate unicast MOH for external calls (including FXS)
• Filename is flash
• Unicast is default
• To change the audio file to a different file, you must remove the first file using the no moh command before specifying a second file. If you configure a second file without removing the first file, the MOH mechanism stops working and may require a router reboot to clear the problem.

telephony-service
  moh MyMoHfile.wav

• Specify the multicast address and the IP addresses of the interfaces that will be propagating multicast MOH to the internal IP phones
• Default port is 2000
• Use private multicast ip range 239.X.X.X
• (Optional) route <ip1> <ip2> specify the interface to send multicast out. Default is to multicast out the source interface that CME is specify to listen under the ip-source-address command

telephony-service
  multicast moh <multicast-ip> port <port-number> route 10.1.2.1 10.1.3.1

• Enable IP Mulitcast routing on router
• And on the LAN/WAN interface and loopback
  • If you don't enable on loopback, PSTN will not work as multicast require an incoming and outgoing IP interface

ip multicast-routing
!
interface FastEthernet0/1
  ip pim dense-mode

• By default the ephone will listen on multicast MOH
• To enable unicast or disable ephone MOH, remove multicast

ephone 1
  no multicast-moh

• Ring reminder that there is a call currently placed on hold

ephone-dn 1
  hold-alert <secs> originator

• Display MOH setting

CCME_Router#show ephone moh 

-------------------------------------
Skinny Music On Hold Status - group 0
 Active MOH clients 0 (max 320), Media Clients 0, B-ACD Clients 0
 File music-on-hold.au (not cached) type AU Media_Payload_G711Ulaw64k 160 bytes
 Moh multicast 239.1.1.1 port 2000 route 10.80.102.2

CCME_Router#