Two important factors that drive your business requirements are:
•
Size of your business, see Market Descriptions
•Requirements for installation and upgrade, see:
–Plan and Prepare for Your System Installation
–Plan and Prepare for Your System Upgrade
–Install and Configure System Components
–Performing Your System Upgrade
–Additional Sites and Services
Review Step 1: Determine Your Requirements 
of the Deployment Methodology chapter in the Cisco Unified Communications System Description.
Collecting Requirements
The following are suggested methods to use in gathering information to plan your network:
•Assess User Requirements—Users want applications to be available on demand in the network. The chief components of application availability are response time, throughput, and reliability. You can assess user requirements as follows:
–Develop community profiles of what different user groups require. Although many users have roughly the same requirements of an electronic mail system, engineering groups using Windows terminals and Sun workstations in an NFS environment have different needs from PC users sharing print servers in a finance department.
–Build a baseline for implementing an internetwork by interviewing groups, forming focus groups, or using surveys. Some groups might require access to common servers, while others might want to allow external access to specific internal computing resources. Formal surveys can be used to get a statistically valid reading of user sentiment regarding a particular service level or proposed internetworking architecture.
–Conduct a test involving representative users in a lab environment. This is most applicable when evaluating response time requirements. As an example, you might set up working systems and have users perform normal remote host activities from the lab network. By evaluating user reactions to variations in host responsiveness, you can create benchmark thresholds for acceptable performance.
•Identify Functionality Requirements—After you understand your internetworking requirements, you can select the specific functionality that fits your environment, such as the level of application availability and the implementation costs for that availability. Fault tolerance and redundancy should be considered also.