This read-create SnmpAdminString (1-64 characters) specifies the tone plan file stored on the media gateway's hard disk, which must already be transferred there via FTP before the conceptual row referencing it is created, or set to the literal value 'BUILT-IN' for a system-provided plan. Administrators use it to point a tone plan entry at either a custom, FTP-uploaded tone definition file or one of the gateway's built-in plans. For example, an admin deploying a custom regional tone set would FTP the file to the gateway first, then reference its filename here when creating the tone plan row.