As Diameter Rf and Ro interfaces are not supported in some networks, interim solutions have been deployed for charging. These include direct CDR generation (often using the MSC’s CDR format to prevent billing domain changes) on each IMS node, other interfaces for online charging (e.g. CAMEL, Radius, etc.).
There is an expectation that the IMS network shall be able to provide all information that is currently provided in a MSC-generated CDR, resulting in proprietary solutions to enable cause codes to be captured (in CDRs, etc.) in a manner consistent with CS domain networks.