With the IP Multimedia Subsystem (IMS) converging different access technologies in common multimedia packet core networks, Alcatel-Lucent developed an innovative standalone IMS converged charging call control service that allows the convergence of online/offline charging for the bearer layer, IMS subsystem layer, and service layer, with call control over different networks. The service provides real-time call/session control during the life cycle of the call/session for voice, data, and multimedia services, such as screening, advanced routing, third-party access, and calling card service. The converged service can interwork with different media resource functions to support IMS and legacy interactive voice response (IVR) and notification services. The converged service can interwork with the online charging system (OCS) to support session- and event-based online charging capabilities, with a charging data function (CDF) and a billing system to support real-time offline charging capabilities. © 2007 Alcatel-Lucent.