Charging has been for a long time on my todo list. Now it’s the time and you can expect couple of posts related to charging, mainly Online Charging. Today we’ll go through the most basic stuff. For details refer to 3GPP 32.240.
Charging is a world of its own, it has its own rules, flows and well, also documentation. To really understand how to properly charge your calls, data, or messages is probably the same or even bigger challenge than to understand the actual service.
GSM/UMTS/EPC networks provide functions that implement offline and/or online charging mechanisms on the bearer (e.g. EPC), subsystem (e.g. IMS) and service (e.g. SMS) levels. In order to support these charging mechanisms, the network performs real-time monitoring of resource usage for those three levels in order to detect the relevant chargeable events.
In general we recognize Online and Offline charging mechanisms. They may be performed simultaneously and independently for the same charging events.