Service interoperability through advanced media gateways

The convergence of telecommunications systems and the Internet causes a variety of concepts for service integration. The focus of the recent research studies and the work of several standardization bodies lies mostly on the interworking of services and the universal service access from end-user systems including both fixed and wireless terminals. All approaches are driven by the concept of providing several technologies to users by keeping the peculiarity of each service alive. But, developments should not only concentrate on media adaptation between VoIP and PSTN, but also consider the adaptation among completely different types of applications as for example E- mail, facsimile, or voice. Unified messaging, which is an already accepted service on the market, provides solutions for conversions of different application protocols into each other. The functionality of converting one medium into another is implemented here in so-called media gateways. This paper provides an overview of the current developments in the area of media gateways. Next, it introduces the basic architecture of an existing CORBA-based unified messaging system and the implementation of media gateways for the adaptation of different services. Finally, both approaches are combined to unified messaging-enabled media gateways that improve the user's reachability because of their capability to adapt services to different kinds of end devices.