Customized Multimedia Ring (CMR) is a set of services. CMR consists of the Customized Ring-Back Tone service and the Customized Ringing Tone service. CMR enables a service provider to deliver customized multimedia ring-back tone to the calling party and ringing tone to the called party. This Recommendation describes the CMR concept, service requirements and CMR functional models in call server based, IP Multimedia Subsystem based and converged network environments.