The project HITEC (H.323-based IP Telephony Control) have dealt with the planning, the implementation and the prototyping of a "PBX VoIP", a managing system for the packet voice communication into an administratively, homogeneous Voice over IP network. The project is aimed to the design of an intelligent "PABX VoIP" system, which includes the functions of the H.323 terminal, the MCU system and the H.323-PSTN gateway in a "Gatekeeper brain" functional element.
The prospective of an integration of telephone and web-based services enabled by the new technology "Voice over IP" has produced the realization of several commercial equipments offering the voice/data integration at different levels; the peculiar feature of these solutions is that they are in compliance with the standards in a more or less pronounced manner. In this framework, the HITEC project, carried out by META center of Consorzio Pisa Ricerche (http://www.meta.cpr.it and funded by Fondazione Cassa Risparmio di Pisa (http://www.fondazionecaripisa.it/), is aimed to the design of a "PABX VoIP" system, which includes the functions of the H.323 terminal, the MCU system and the H.323-PSTN gateway. Besides these, the system is characterized by the adding to the "gatekeeper" traditional management functions, new auxiliary functions in an entity denoted as "GateKeeper Brain" (GKB).
These new functions are necessary to support the H.323 entity in the implementation of services either already defined in the H.323 systems, such as the supplementary services of the H.450 series, or not yet standardized. The innovative approach of the HITEC project is the realization of a PABX VoIP prototype in compliance with the H.323 standard, and characterized by a limited hardware requirements (a simple PC with Linux O.S. and cards needed for the implementation of the gateway and GKB functions). These features should permit to the designed prototype to provide with a lower cost the same functions of commercial system already present in the market (legacy PABX or VoIP architectures often based on proprietary solutions), to guarantee the interoperability with system compliant to H.323 standard, and to make available a platform where users can develop new services exploiting the voice and data integration. An example of such integration consists in the introduction of call-center services for supporting traditional web-based services such as home banking and electronic commerce. This enhancement permits to the service operators to offer vocal support, which can give an important added value to the customer.
The project aims also at overcoming the limits of the H.323 architecture maintaining one rigid adhesion to the standard mechanisms, thanks to the introduction of new control centers of the H.323 zones. The intelligence of a H.323 architecture is distributed on the gatekeepers, whose management operations (authorizations management of the H.323 clients, accounting of the calls, etc.) are not detailed by the H.323 standard. Thus, at the state of the art the implementations of gatekeeper are characterized either by a rather ingenuous management plane (for example, it is not possible to insert policy on the customers enabled to register themselves and to use the communication services), or by proprietary control architectures (an example is the AVVID architecture of the Cisco Systems).
The innovative contribution of this project is the definition of a system where are located the management functions (the "GKB"). The GKB is defined in order to increase the flexibility and the capillarity of the management plane of the VoIP architecture maintaining meanwhile the compatibility with the H.323 standards. In the project vision, the gatekeeper interacts with the GKB and depends on it for whichever decision related to the normal procedures of H.225/H.245 protocols. The transfer of some typical functions of gatekeeper in the auxiliary subsystem GKB and their integration with management function of the H.323 zone, produces two main advantages.
The realization of the PABX VoIP system is based on the approach of open architecture "Openh323", on platform IA32 with Linux O.S., according to the paradigm application/server. The advantages of this solution consist in the high reliability, flexibility and robustness of the Linux O.S. and in the perfect conformity to the H.323 standards implemented by the Openh323 library. Furthermore, this library constitutes a powerful development environment of H.323 applications, and, therefore, it is considered not only by academic and standardization entity, but above all by several manufacturers.