The Cisco MCS 7835-H1 Unified CallManager Appliance (MCS 7835-H1) is a high-availability server platform for Cisco Unified CallManager 5.0 and an integral part of a complete, scalable architecture for a new generation of high-quality IP Communications solutions for enterprise data networks. Delivering the high performance and availability that today's enterprise networks demand, this solution is easy to deploy and highly cost-effective. The server appliance is preinstalled with an operating system and Cisco Unified CallManager 5.0; it is fully operational upon startup, requiring entry of just a few configuration items such as IP address and domain. At just 2 rack units (2RU) high, the Cisco MCS 7835-H1 offers tremendous power in a low-profile chassis that minimizes rack space. It supports up to 2500 IP phones per appliance and up to 10, 000 IP phones in a cluster configuration.