The topic of policy-based management is introduced. Its specific application by the ACCENT project to call control is then discussed. The APPEL policy language supports regular policies as well as resolution policies that deal with conflict handling. The core APPEL language can be specialised, e.g. for call control. Ontologies are introduced as a means of capturing domain-specific knowledge -- here, about calls. It is seen how this has allowed the ACCENT policy system to be generalised for use in a variety of domains. This is supported by a stack of interrelated ontologies: for generic policy aspects, for a policy definition wizard, and for call control. The approach has been integrated with the ACCENT system, allowing its extension for policy-based management in new domains.