/mcpMulticast Audio Source Unicast Audio Source For multicast users, this announcement is not heard. An MOH audio source may be configured with an initial (greeting) announcement, which will be played to unicast held parties. For unicast MOH users, this announcement is heard from the beginning. Multicast MOH conserves system resources and bandwidth. The additional MOH streams can have a negative effect on network throughput and bandwidth. Can be problematic in situations in which a network is not enabled for multicast or the endpoint devices are incapable of processing multicast. Extremely useful in networks in which multicast is not enabled or devices are incapable of multicast. Includes managing devices, IP addresses, and ports. Includes managing devices only. Administrators must define at least one audio source to allow multicasting. To define Music On Hold servers for multicast, first define the server to allow multicasting. No requirement to define the Music On Hold server. Functions only if both media resource groups and media resource group lists are defined to include a multicast Music On Hold server. For media resource groups, you must include a Music On Hold server that is set up for multicast. These servers are labeled as (MOH) [Multicast]. Also, check the Use Multicast for MOH Audio check box when you define a media resource group for multicast. Functions without configuring MOH audio source, MOH server, or media resource group list. The Multicast MOH Direction Attribute for SIP service parameter determines whether Cisco Unified Communications Manager sets the direction attribute of the Session Description Protocol (SDP) in its multicast Music On Hold (MOH) INVITE message to sendOnly or recvOnly. If your deployment uses SIP phone uses Release 8.4 and earlier for Cisco Unified IP Phones 7940 and 7960, or SIP phone uses Release 8.1(x) and earlier for Cisco Unified IP Phones 7906, 7911, 7941, and 7961, set this parameter to sendOnly. Otherwise, leave this parameter set to the default value, recvOnly. Note Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs 628 Custom Features Unicast and Multicast Audio Sources