For Release 5.0(2), Cisco developed a variety of site models as standard architectures. These models were tested and optimized for maximum efficiency and performance. You can derive your network design by choosing the deployment model that most closely matches your business and then adding the specific features and applications that meet your business needs.
Review the information in the Tested Deployments and Site Models 
chapter of the System Test Architecture Reference Manual for IP Telephony: Cisco Unified Communications Release 5.0. Specific topics in this chapter are listed here:
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Multi-Site Distributed Deployment Options