ABSTRACT
Telephony over Internet Protocol (IP) has succeeded to federate a large number of researchers and engineers in both standardization and industrial fora. Among other results, several protocols, such as Session Initiation Protocol (SIP) (Rosenberg 2002) and H.323 (ITU-T H.323 1998) have been proposed and promoted for the deployment of IP-based telephony service offerings. These protocols have been introduced progressively into operational platforms. Recently, new architectures such as IP Multimedia Subsystems (IMS) (Camarillo and Garcia-Martin 2005) and TISPAN Telecommunications and Internet converged Services and Protocols for Advanced Networks (TISPAN) (TR180001 2006) have been proposed to meet service providers’ requirements (mainly to implement the fixed-mobile convergence). Most current big service providers deployments are inspired from IMS and/or TISPAN architectures.
