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Traffic Analysis for Voice over IP 
white paper—Provides background information on various traffic analysis concepts and features that are applicable to Voice over IP (VoIP). This document presents fundamental traffic theory, several statistical traffic models, application of traffic analysis to VoIP networks, and an end-to-end traffic analysis example.
•Cisco Unified Communications Manager Capacity Tool 
—Calculates the minimum number of active subscribers that are required to support a given installation. Input consists primarily of quantity and usage information on the various device types that are supported in a Cisco Unified Communications Manager system.
•Bandwidth Calculators 
—Calculate bandwidth for CTI OS, CAD, and HDS WebView withfor contact center systems. The output from these tools can also be used as input to the Cisco Unified Contact Center Express Configuration Tool 
and the Cisco Unified Communications Manager Capacity Tool 
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•Cisco Unified Contact Center Enterprise Sizing Tool (Unified CCE Tool) 
—Helps size the Unified CCE resources required to meet the needs of a specific contact center. It also provides data that can be used as input for other capacity planning and sizing tools, such as the Cisco Unified Communications Manager Capacity Tool, and the Unified CVP and Cisco IP IVR sizing tools.
In addition, these third-party traffic engineering tools are provided for your reference:
•Online Erlang traffic calculators
The Cisco Unified Contact Center Enterprise Release 7.x SRND also includes information on sizing your contact center components.