All Media Gateways must have same set of voice prompts.
To support this, in Prerequisites section, following additional information is added.
For proper configuration, all Media Gateways (MGUs and Media Servers) must have the same set of local voice prompts installed. However, If all Service Nodes are configured to use Media Server (SIP or MSCML interface) for RVA and MOH, then only Media Servers need to have voice prompts installed.
For more information, see the following document: