In this paper we explore the use of group communication technology, developed in the Horus project to implement a reliable and scalable distributed IN coprocessor. The proposed implementation can handle up to 20,000 calls per second with 12 computing nodes, can tolerate a single node failure or recovery, and can recover from periods of overload. Our work suggests that group communication technology can bring substantial benefits, including scalability, fault-tolerance, and real-time responsiveness to the most demanding telecommunications applications.