A packet telephony appliance includes a Euphony network processor that integrates networking and DSP functions to provide a low cost and efficient solution in building a networked appliance. In particular, a Euphony ATM Telephone (EAT) is built around the Euphony network processor. The EAT uses a real-time operating system to provide predictable processing and networking support. The EAT implements IObufs, which provides a unified buffering scheme that allows zero-copy data movement. Furthermore, the EAT uses an Event Exchange (EVX), which provides a flexible mechanism for event distribution, allowing software modules to be composed together in an extensible manner. EVX and IObufs are used together to provide highly efficient intra-appliance communication. The EAT provides a platform that can evolve gracefully to support new protocols, advanced telephony services and enhanced user interfaces.