Customized multimedia ring (CMR) is a set of services that allows subscribers to customize the media used for ring tone presentation to the called/calling party. CMR consists of the customized ring-back tone (CRBT) service and the customized ringing tone (CRT) service. From the user point of view@ subject to the media capability of the terminals@ the user experience of the service is similar across various network environments@ but from the service architecture perspective@ each environment has its own functional models and requirements. This Recommendation provides: ?C CMR general description; ?C CMR service requirements; ?C CMR functional models in call server-based@ IMS-based and converged network environments.