 the satisfaction of your organization's expectations: Analyze the cost. Assess traffic volumes and patterns. Assess network design implications. Determine an emergency call policy. Define a pilot user community. Define the production user community phases. Evaluate future new services. Assess security implications. Cost Analysis Do a thorough cost analysis using the material presented in Chapter 4. Compare the results of this analysis to an objective view of your current PSTN access expenditures and expected future costs. Keep in mind that providers in certain geographies might drop their traditional PSTN PRI prices in the short term to maximize revenue on infrastructure already in place, whereas in the long term, prices might go up as the providers find it difficult to maintain older equipment in parallel with the newer network technologies. Assess Traffic Volumes and Patterns Ensure that you understand what your current PSTN traffic patterns constitute. Understand what call flows are necessary to sustain your business and what the traffic volumes of particular types of calls are, for example, international calling, long distance calling, and local calling. Understand inbound and outbound traffic patterns, office user and home or remote user traffic patterns, and traffic patterns of your different depart- ments or organizations. When you reach the step at which you start using the SIP trunk for the pilot user community, this analysis can help you determine which user communi- ties or which call types (and in what sequence) to place into production SIP trunking. 246 SIP Trunking In a large network you cannot (and should not) migrate your entire network to SIP trunk- ing overnight. It is both impractical and risky. You should define discrete steps and differ- ent user communities or call types to start using SIP trunking at a certain stage. Assess Network Design Implications Review quality of service (QoS) and call admission control (CAC) policies in the network to ensure coverage of new call flows. Potentially, 