ABSTRACT
Recently, IMS technology has signifi cantly changed the existing billing model for traditional Internet services. An effi cient IMS charging system is important for an operator to create revenue. For example, mobile users can send text messages, pictures, or videos while they are simultaneously engaged in Voice over Internet Protocol (VoIP) voice call sessions. This means that pre-event or mid-event authorization for online services should be performed. As the authors in [2] state: “Billing can now become a service in and of itself, as billing, in essence, will run like a service, with authorization, charging and rating all running as low-latency services within the IMS architecture.” Therefore, the design and management of new sophisticated functions and protocols to support fl exible and convergent charging mechanisms are essential. This chapter provides a comprehensive picture of the characteristics and practical aspects of online and offl ine charging based on the latest efforts undertaken by the 3GPP specifi cations. We describe the IMS architecture and the related charging components. Also, the offl ine and online charging solutions implemented for IMS calls will be discussed.
