af431fc3_r_Voice_Conferencing___DocWiki__Action
[Field] Media Resource Group List [Action] 
(Optional) If Cisco Unified MeetingPlace-supported endpoints are registered to this Cisco Unified Communications Manager, then we recommend that you choose one of the following to prevent conference calls from being disrupted by music whenever a user places a call on hold: Default value of . A Media Resource Group List that does not contain music on hold resources. Note: See Configuring Cisco Unified Communications Manager: Music On Hold.
Cisco Unified MeetingPlace, Release 7.0 -- How to Configure Call Control for Voice Conferencing - DocWiki