The objective of this study item is to study requirements and potential new capabilities in 3GPP that need to be standardized for the CAT service, especially additional features for roaming and interoperability support. The present document specifies the requirements and technical implements for Customized Alerting Tone (CAT) service in CS domain and the developments in PS domain. Basically this TR is considering voice services, though interaction with MITe [2] services will be studied. Also Multi-media CAT will be taken into consideration, so the CAT user may experience favourable songs, multi-media clips or other customized alerting tones.