A CDE Definition

(Unstructured Supplementary Service Data) A messaging function in GSM cellphones. Unlike regular text messages, USSD messages travel over GSM signaling channels and are used to query information and trigger services with the phone carrier. See CAMEL.

(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. Phase 1 covers basic features such as call waiting and forwarding. Phase 2 supports 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.