Analog telephone networks, are gradually giving way in favor of new Internet-based communication systems (VoIP). However, the diversity and heterogeneity of systems and suppliers prevent users from communicate with their contacts on an uniform and simple way. In this paper a new VoIP multiprotocol and multidevice system, extensible by plugins, is presented. Heterogeneous character has lead us to the need of considering several different communications mechanisms at present. The usage of common devices for telephone communications has also been considered. A complete system has been developed in order to integrate all possible components of a VoIP system.