CAMEL Standards (Phase 1-4) were standardised well before Diameter (DCCA), Gy, Gx, Sy, Policy (PCRF), etc..
For online charging the basic functionality as now defined by IETF Diameter Credit Control Application (DCCA) is used. The basic structure follows a mechanism where the online client (CTF) requests resource allocation and reports credit control information to 3GPP OCS (Online Charging System).
CAP V3 can be used for MO-SMS Charging (CAP V4 supports MT-SMS).
VBR/ Wallis Dudhnath