Enables or disables Music on Hold in Attendant and prevents the user from modifying the setting in Attendant Options. If ...

"Enables or disables Music on Hold in Attendant and prevents the user from modifying the setting in Attendant Options.  If this policy is set to a non-zero value, then Music on Hold is disabled, and the user setting in Options is disabled.  If this policy is not set or set to zero, then Music on Hold is enabled, and the user setting in Options is also enabled, unless MusicOnHoldAudioFile is set.  Note: In the case where MusicOnHoldDisabled is set and non-zero, and MusicOnHoldAudioFile is also set, Music on Hold is disabled (MusicOnHoldDisabled takes precedence)."