The Cisco MCS 7845-H2 Unified CallManager Appliance is a high-availability server platform for Cisco Unified CallManager 5.1 and greater and an integral part of a complete, scalable architecture for a new generation of high-quality IP communications solutions for enterprise data networks. It delivers the high performance and availability that today's enterprise networks demand - and it is easy to deploy and highly cost-effective. The server appliance is preinstalled with an operating system and Cisco Unified CallManager 5.1 or greater. 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 7845-H2 offers tremendous power in a low profile chassis that minimizes rack space. The appliance supports up to 7500 IP phones per appliance and 30.000 IP phones per cluster.