(Customized Application of Mobile network Enhanced Logic) A set of ETSI standards for extending landline intelligent network (IN) telephony services to the data services of GSM, GPRS and UMTS mobile systems. CAMEL functions were added in phases; highlights are basic features such as call waiting and call forwarding in Phase 1, while Phase 2 added support for prepaid calling and unstructured supplementary service data (see USSD). Phase 3 supports roaming; Phase 4 adds multimedia services, and Phase 5 provides seamless prepaid roaming. See CAP.