In recent years, thanks to new IP protocols like SIP, telephony applications and services have evolved to other and combine a variety of communication forms including presence status, instant messaging and videoconference. As a result, advanced telephony applications now consist of distributed entities that are involved into multiple heterogeneous, stateful and long-running interactions (sessions). This evolution complicated significantly applications development and calls for more effective solutions. In this paper, we explore the adoption of components for addressing this issue, focusing specifically on the management and coordination of the numerous and various sessions occurring in such applications. The paper presents CIAO, a domain-specific and hierarchical component model for SIP applications. CIAO combines three kinds of component that are Actor, SessionPart and Role and manage them dynamically in accordance with real SIP sessions. By using these features, we are able to break the complexity of SIP entities and provide flexibility for their development. CIAO is implemented above OSGi to experiment the building of concrete SIP applications and enable their dynamic adaptation.