If the COR of the user extension that places the call on hold supports music-on-hold, a caller on hold hears the music source that is assigned to the partition at which the call initially terminates. For example, if the system first routes a call to an Communication Manager Messaging automated attendant, and then routes the call to the appropriate tenant partition, the caller who is on hold hears the music source of the Communication Manager Messaging automated attendant. The caller who is on hold does not hear the music source of the tenant partition to which the system routes the call. Likewise, if a caller in tenant partition 2 makes an out-going call that uses the trunk groups of tenant 3, the caller hears the music source that is assigned to tenant 3. If the COR of the called extension does not support music on hold, the caller hears nothing.