Charging in the IP Multimedia Subsystem: A Tutorial

The IP multimedia subsystem enables a service-rich communication landscape and the convergence of mobile and fixed networks. However, IMS solutions can succeed only when charging for these new services is supported in a flexible and efficient manner. To meet the new challenges, the 3GPP recently introduced a generic charging framework. In this article we give a short overview of the 3GPP charging framework and then describe how IMS charging works with in this framework. To illustrate IMS charging, we discuss an IMS scenario in which three persons with different payment methods conduct a teleconference.