A high-availability design provides the highest level of failure protection. Your solution may vary depending upon business needs such as:
Tolerance for call failure
Unified CVP can be deployed in many configurations that use numerous hardware and software components. Each solution must be designed so that a failure impacts the fewest resources in the contact center. The type and number of resources impacted depends on how stringent the business requirements are and the design characteristics you choose for the various Unified CVP components. A good Unified CVP design is tolerant of most failures, but sometimes not all failures can be made transparent to the caller.
Unified CVP is a sophisticated solution designed for mission-critical call centers. The success of any Unified CVP deployment requires a team with experience in data and voice internet, system administration, and Unified CVP application configuration.
Before implementing Unified CVP, use careful planning to avoid costly upgrades or maintenance later in the deployment cycle. Always design for the worst failure scenario, with future scalability in mind for all Unified CVP sites.
In summary, plan ahead and follow all the design guidelines and recommendations presented in this guide and in the latest version of the Cisco Unified Communications Solution Reference Network Design (SRND) Based on Cisco Unified Communications Manager, available at:
For assistance in planning and designing your Unified CVP solution, consult Cisco or certified Partner Systems Engineer (SE).
Unified CVP Call Server High-Availability Component Consideration
In the other chapters of this document, the Unified CVP Call Server is described as a single component because it does not need to be described in depth. When discussing Unified CVP high availability however, it is important to understand that there are actually several parts to this component:
SIP Service—Responsible for processing incoming and outgoing calls with SIP.
ICM Service—Responsible for the interface to ICM. The ICM Service communicates with the VRU PG using GED-125 to provide ICM with IVR control. The ICM Service was part of the Application Server in previous releases of Unified CVP, but now it is a separate component.
IVR Service—Responsible for the conversion of Unified CVP Microapplications to VoiceXML pages, and vice versa. The IVR Service was known as the Application Server in previous Unified CVP versions.