'Service Catalogs' limit the 'Available Service' picker to only itself or it's parents. When a 'Service' is aged, the Catalog remains on the Service. In order to ensure a Service is available for use on all Catalogs, it is recommended to once a week/month set all available services to the parent Catalog (e.g. Phones). For Services associated with a 'Service Pool', depending on the Organizational needs, it may also be needed to associate the Service to the Pool. Once this process has been completed, the Available Services will be present for all desired Catalogs, rather than only for the specific Catalogs it was previously associated with.
If your Organization would like this process to be automated, contact PCR for details on setting the process up.